By Catherine Hiller

St. Martin's. 277 pp. $16.95

"17 Morton Street" is one of several novels this season that treat the subject of sisterhood -- not in its universal sense, but in the particular. Catherine Hiller has created three thirtysomething sisters, housed them in a comfortable New York brownstone, and set about describing the intense intimacies they share and the obsessive jealousies that divide them. Sibling rivalry is a fertile subject for literary exploration as it reflects and -- possibly -- prefigures the complex and confusing competition that so frequently disrupts sisterly relations on a more universal level.

With a zesty, zingy style, Hiller (who also wrote "Old Friends From High School") first introduces Sara, the eldest Jennings sister, as an earth mother-type who automatically serves her son moussaka "from the casserole without the eggplant." Perri, the most beautiful sister, wears "two shades of color on her lips ... three around her eyes," and is an irrepressible vamp. She assesses other women's sexual powers like a man gauging the size of a possible antagonist. Lucy, the youngest, is the painfully plain intellectual who believes that "most young girls would rather be beautiful than brilliant -- even the brilliant ones."

As in life, the sisters constantly play out the well-defined roles assigned them in the original unwritten script developed during their childhoods. It is only the arrival of an Italian au pair, who turns out to be an attractive young man, that shakes things up. Carlo is the catalyst for the boisterous "sex comedy" that evolves, complete with mistaken identities, frequent hot-tub sex, the death of one lover "in the saddle," sisters unwittingly involved with the same man and so forth. Despite a lot of ritualized "romps," there are so many crisp insights en route to the happy ending that any good-natured reader will find this novel a real treat.

Sara, the only married sister, has to contend with her kids, an unplanned pregnancy, a cranky husband who throws a fit about the prospect of a third child ("They'll outnumber us!"), and many other issues, such as the fact that cooking isn't much fun anymore since heavy-cream-and-three-sticks-of-butter recipes have gone out of style in a big way. Shortly after Sara turns herself "inside out" to deliver her third baby, her husband leaves and she initiates an affair with her au pair. This liaison is the least convincing of all the couplings in the story.

Meanwhile, Perri copes with career problems, romantic obsessions and difficult decisions about what kind of underpants to wear on a first date so the guy won't know she's been expecting, or planning, a sexual encounter. A marijuana addict and a sexual mess, Perri compulsively creates crushes on non-responsive men to preoccupy and torture herself. But despite all her craziness, Perri works with passionate commitment on a documentary film about the genesis and growth of the National Writers Union. Her cinematic efforts offer an important insight into her character as well as a factually accurate and interesting account of the new union, which Perri characterizes as a "David" against the Goliath of the publishing world.

Lucy, damned with "an interesting face" and "a wonderful mind," teaches psychology at Columbia University and seems destined for a loveless life of quiet desperation on the top floor of 17 Morton St. Although Lucy is more self-reflective than either of her gorgeous sisters, she still uses their hectic lives as a standard for her own behavior. "I leaned against his shoulder. I was thirty-two years old, and it was the first time I'd been on a date at the movies." She constantly compares her plainness to their beauty, actually afraid she's cheating her students who "want to fall in love. They want the professor's charisma to buzz them, make them hum and glow. Then their burning interest in the teacher may even extend to the subject."

Catherine Hiller's writing explodes with surprising insights, juicy characterizations and familiar truths. The complex relationships among her three major characters are a rich source of material. Indeed, the interaction of these biological sisters offers a sharp paradigm for analyzing the behavior of real, non-sibling females who also seek a sanctuary in sisterhood.

The reviewer is a novelist whose books include "Hot Flashes" and the forthcoming "Current Affairs."