Older women hooking up with younger men? It's becoming mainstream, as women in great shape and good health find themselves attracted to men many years their junior.

"Younger guys are more fun," says Mary Walsh, 59, a single woman and nurse. "Men in my age group are fat, have high cholesterol and are not in good shape."

A 2003 AARP survey on sexuality among single Americans ages 40 to 69 found that 35 percent of women want to date younger men, and 34 percent are. Three percent of women date men 15 or more years younger, 5 percent date men 10 to 14 years younger, and 11 percent date men 5 to 9 years younger.

There's a manual for such women. Valerie Gibson, author and sex and relationships columnist for the Toronto Sun, titled her guide for older women dating younger men "Cougar" (Firefly Books, $12.95).

Once a derogatory term for the stereotypical older woman trying too hard to look young, sexy and available to younger men, "cougar" no longer implies an unsavory predator, Gibson says: "A cougar is a beautiful animal: sleek, powerful and in control."

"It's an important trend, it's a significant trend," says Duffy Spencer, a social psychologist on Long Island, N.Y., and host of the radio talk show Just Relationships. "It makes malefemale relationships topsy-turvy. It turns everything on end."

In the past, women tended to hook up with men their age or older.

"This is moderating," says Pepper Schwartz, a professor of sociology at the University of Washington in Seattle.

Women are staying sexual into old age. They have careers, higher incomes, a wealth of experience and good connections.

"They bring something to the relationship," Schwartz says. "Their antennae are out."

Susan Swartz, a relationship columnist and author of "The Juicy Tomatoes Guide to Ripe Living After 50" (New Harbinger Publications, $16.95) says age isn't the bugaboo it used to be.

"We have choices. And we think we should have as many choices as men," she says.