DESPERATELY SEEKING SUSAN" is a delirious comedy of errors that mixes the tenets of "Dressed for Success" with "Being There" and "Tootsie": You are what you wear. You are who others think you are. And you've got to walk a mile in another girl's high heels to elevate your consciousness.

Actress Rosanna Arquette and video vamp Madonna star in this wonderful new-wave mix-up, directed by the difficult but dynamic Susan Seidelman. Her first film, "Smithereens," shares its East Village setting with "Susan" as well as its "searching" theme. Leora Barish, in her first solo writing effort, bases her comedy on a convoluted case of mistaken identities.

Arquette is angelic as the outsider Roberta looking to get in, a quixotic New Jersey housewife kept in a yuppie palace by her husband, the hot tub man (Mark Blum). Roberta finds romance in the Personals where lovers Jim (Robert Joy) and Susan carry on a high- visibility affair. Roberta's curiosity overwhelms her and, through various coincidences, Susan's identity becomes hers.

Madonna, a cast-iron delight as the free- spirited Susan, plays down her celebrated assets -- her pretty pipes and her belly button -- and acts with perfect hauteur, like Morris the Cat coaxed with gourmet catfood. Her Susan is an underground Holly Golightly, dressed in nasty snazzy underwear and getting Cheeto fuzz on her fancy dress gloves. She's as shrewd as Roberta is naive, but both have the same opinion of New Jersey. "We all thought you were dead," says a friend. "Just in Jersey," Susan replies.

Aidan Quinn, the handsome, unheralded star of "Reckless," costars as a mild-mannered, movie projectionist who winds up with the wrong girl. After a harsh encounter with the sidewalk, Roberta wakes up with amnesia ihis arms. Both of them, and the lurking villain, think she is Susan, who thinks Roberta is somebody else all together. It's a happy scramble full of surreal comic vignettes, cult stars, such as Anne Carlisle, Richard Hell and Richard Edson, and vivid settings by designer Santo Loquasto.

And as we all like to keep up, a word about trends: Amnesia, if memory serves, struck last summer's "American Dreamer," a housewife who thought she was a glamorous detective; and Alan Bates in last week's "Return of the Soldier." Films with that theme are becoming less memorable. But "Desperately Seeking Susan" is an unforgettable exception. See it before you get konked in the head.

DESPERATELY SEEKING SUSAN (PG-13) -- At area theaters.