Annie Hall would love it.

The favorite togs of young fashion-conscious woman this fall on the Boulevard Saint Germain, the Georgetown of Paris with its boutiques and street fashions, are oversized jackets and vests, big, sloppy V-neck sweaters, ties and men's hats, floppy skirts and pegged corduroy pants.

Despite the popularity of the Woody Allen-Diane Keaton comedy here over the last two months, the look has less to do with the film than with an oversize menswear look for women initiated by Paris designer Kenzo for his JAP boutique and picked up by many an imitator. It showed up often in the ready-to-wear collections for spring displayed to buyers and reporters in the last two weeks.

American buyers pay careful attention to what they see on Paris sidewalks because a fresh look on the Saint Germain has a way of turning up not too long after on the streets of Manhattan and, a bit after that, in Washington and other cities. Paris designers not only study the trends, many of them live the latest look personally.

This year's version bears little resemblance to the primmer, neater, more self-conscious style of many Washington women.

The ingredients are often alike. But the final turn-out is rarely duplicated because it builds on what the individual already owns, rather then anything assembled by a store or boutique.

"My jacket is fairly new, but the hat and skirt are from an antique clothing store, the wool scarf from a trip to London last year, and the boots I've had for a long time," said a young part-time Paris model taking inventory of her attire last week.

Big blousons show up in leather as well as knits and wool, worn both by men and women. Jackets are never neat and trim, but oversized to give softness and a relaxed look with sleeves pushed up, the collar turned up, and a muffler often tied around the neck.

Prizzy hair has fizzled out. The favorite hair style is the long braid, often a Chinese-style pigtail trailing down the back. Hats, pulled down to the eyebrows somewhat mannishly, are funny knit caps with tiny rolled edges.

Pants are not the strict, man-tailored cut but a softer, often pegged variety. Blue denim jeans appear rarely now, but skintight corduroys are still apparent poking out from some of the biggest blouson sweators and jackets imaginable.

Boots remain popular. The above-ankle boot a la Saint Laurent is newest, but the straight-cut boot on a high heel or wedge and high-heeled shoes are far more common. There is an occasional carryover from the summer - little-girl sandals from Sacha sometimes worn with socks, or high-rise sneaker'shoes with socks rolled down over the top.

Men, too, take fashion in a far more relaxed way than men in Washington. Vests have given way to sweaters and stiff jackets to unlined blouson shapes or vests, particularly on weekends. Except for the strict business suit, ties have been abandoned and if anything takes its place, it is the muffler.

With luck it might happen here.