Not long ago while doing morning rounds at the Hebrew Home for the Aged in Riverdale, the Bronx, Edna Adams, a nurse's aide, knocked on a resident's door. As was her habit, when she didn't hear an answer, she pushed it open, and found two of her patients — each over 80 and with Alzheimer's disease — nude and making noisy, passionate love.

With barely a hint of surprise, she did exactly what she was supposed to: she whispered "excuse me," closed the door and made a mental note to come back and make the bed later.

"When I first started, I was shocked and shy when I would see them having sex," said Ms. Adams, 46, who has worked at the Hebrew Home for 17 years. "But now I've seen it so often that I just think, if two of them like each other and they are together, why shouldn't they be allowed to have sex?"

Ms. Adams knew to let nature take its course, thanks to a highly unusual set of policies and procedures concerning sexual expression and the nursing home resident, introduced at the Hebrew Home in 1995. The Hebrew Home's policy states that "residents have the right to seek out and engage in sexual expression, including words, gestures, movements or activities that appear motivated by the desire for sexual gratification."

Over the past several years, all members of the Hebrew Home's 2,000-member staff have received comprehensive training and have been schooled on residents' sexual rights and needs.

This spring, the nonprofit 1,100-resident facility went a step further, creating "Freedom of Sexual Expression: Dementia and Resident Rights in Long-Term Care Facilities," a detailed and fairly explicit training video to provide extra help to staff members dealing with specific sexual situations involving residents, particularly those with deteriorating mental capacity.

Financed by a grant from the New York State Department of Health, the video has also been distributed free to all 677 homes for the elderly in New York State.

"We understand that sex is the outgrowth of intimacy, affection and caring," said Daniel Reingold, executive vice president of the Hebrew Home. "Our goal is to encourage those emotions while also being aware of the rights and safety of others."

Narrated by the actress Anne Meara, the 20-minute video illustrates several graphic examples, apparently common, including a relationship between two women, a sexual coupling that is no longer consensual, and a resident who is masturbating in public. (In the video, staff members are instructed to leave the women alone; to pull the couple apart, gently but forcefully; and to take the resident to the privacy his room.)

It also features poignant interviews with the daughters of two residents who met in the home, fell in love and maintained a loving sexual affair.

Experts describe the Hebrew Home as one of the very few nursing homes in the country, if not the only one, to address the issue of sexuality in this kind of comprehensive, detailed manner.

The American Health Care Association, a federation of 12,000 nursing homes and other long-term care facilities, sells a staff training manual about sex in long-term care and offers workshops on it at its annual convention.

But most of the nation's 17,000 facilities for the elderly offer only fleeting education for staff members on the subject. Though it is a growing concern, few homes have formal guidelines or policies. Uncomfortable with the idea of older people having sex at all, many centers deal with situations case by case, if at all.

"Sex knows no age limit, but it's very difficult to talk about as far as the elderly since it gets into so many stereotypes and taboos," said Dr. William L. Minnix Jr., president and chief executive of the American Association of Homes and Services for the Aging, a 5,600-member organization of nonprofit centers.

"But we are not talking about junior high school students; these are 80-year-old adults with needs and feelings, and they have the right to sexual pleasure late in life when there are so very few pleasures left," Mr. Minnix said. Still, he added, so many have declining mental faculties that complicated, delicate issues often arise.

Stella Henry, a registered nurse and a co-founder and director of Vista Del Sol, a long-term care center for the elderly in Culver City, Calif., said she was surprised by her own response when her 86-year-old mother moved into her facility and began a relationship with another resident.

"I was shocked at how I felt," said Ms. Henry, whose mother has diabetes, congestive heart failure and the early stages of dementia. "To me, she wasn't supposed to be involved with anyone or have any kinds of sexual needs. I was afraid people would laugh at her, seeing her as some kind of goofy old woman."

Ms. Henry says she now is more comfortable with her mother's relationship, though she's quietly relieved that her mother and her male friend, who is 90, are probably limited to kissing, caressing and holding hands.

"I now realize that this has been extremely good for her," said Ms. Henry, who conducts occasional training sessions with her 80-member staff about sex and the elderly.

"My mother to used sleep until noon and rarely bathe. Now she gets up at 7:30, bathes, puts on makeup and makes sure her hair is done."

The Hebrew Home does draw the line, banning relationships with minors and those that involve public displays. The policy also prohibits acts involving people with seriously declining mental faculties and acts that are nonconsensual.

"Basically, our policy encourages intimacy and positive physical touching," Mr. Reingold said. But with the prevalence of dementia, he added, "there are gray areas of both privacy and consent."

Studies show that about half of elderly nursing home residents have some form of dementia, and a majority take psychiatric medication. "There is a lot of dis-inhibition with dementia," said Dr. Judith H. W. Crossett, an associate professor of psychiatry at the University of Iowa, who supervises the psychiatric care of residents at 20 nursing homes.

"What prevents you from acting on impulses can fade with dementia, similar to how inhibitions recede with alcohol. Some men misidentify every elderly woman as their wife."

Sometimes it is the family that demands the end to a relationship. "We've had cases of two people that got together, but one of them was still married to a spouse that was dwelling in the community," Mr. Reingold said. "If a family member says, `No, I don't want my husband or wife, who is living in your nursing home, having sex with another person,' we have to respect that. We would not permit a sexual relationship that the family said no to."

An 83-year-old woman and her 92-year-old boyfriend, residents at the Hebrew Home, are glad their children approve of their relationship, though they asked that their names not be printed. The couple, who have lived at the home for about nine years, have been together almost as long.

Despite her walker and his wheelchair, they make love in his room twice a week. He is the first man she has slept with, she said, since her husband died in the 1970's. "I never thought I'd fall in love again," she said. "It feels good, just like kids. It's nice to have a man again."

He is more philosophical, but just as in love. "We are able to have what we consider a normal, happy, loving relationship because of the home's policy," said the man, who has Parkinson's disease. "We are citizens, and we have a legitimate right to privacy. As long as you are not making a spectacle of yourself, anything you do as two consenting adults is considered good."