Arnold Scaasi’s fans gathered last night at a party for his new book, “Women I Have Dressed (And Undressed)” (Scribner).

Longtime pal Liz Smith gave the toast, describing the first-time author as “full of infinite variety” and “the only man who still looks good in a bikini.”

Most people know him as the man who, for nearly 50 years, has dressed “famous and rich and often spoiled women,” as he describes his clients in his book.

To work with such clients, Mr. Scaasi explains, “You have to know their lifestyle, and very often, become part of it. You must go to the places they inhabit…and of, of course, one must attend the charity balls… Sometimes it’s tedious, but often it’s glamorous and wonderful fun!”

There was nothing tedious about last night’s party, held at Le Cirque 2000. Guests included Barbara Walters (a bit tired after her big farewell party Wednesday night), Ann Ziff (who said she has too many Scaasi gowns to count), William Ivey Long (who is working on the revival of La Cage Aux Folles), Joan

Rivers, Tommy Hilfiger, Mary McFadden, Arlene Dahl, Steve Schwarzman, Emilia Fanjul, Robert Caro, Somers Farkas, Beth Rudin DeWoody, Jamee Gregory, Gayfryd Steinberg, Amy Fine Collins, and Peter Rogers.

Some of the women dressed in Scaasi were Muffie Potter Aston, Marjorie Gordon (who once worked for the designer), and Barbara Goldsmith (who is publishing a book on Madame Curie in November).

Mr. Scaasi (ne Isaacs, in Montreal) came to New York in 1953 and landed a job with couturier Charles James. By 1959, he was living in the Stanford White-designed house on 56th Street, selling his designs across America, and designing bespoke clothes.

Some of the women he writes about in “Women I have Dressed” are Joan Crawford, Jacqueline Kennedy Onassis, Laura Bush, and Senator Clinton (Mr. Scaasi states he’s a registered Independent).

Mr. Scaasi kept his remarks brief. “People ask me why I wrote this book. My answer is I’ve been taking so much all my life in New York that it’s time to give back.” He’s donating a percentage of his royalties to the Breast Cancer Research Foundation, God’s Love We Deliver, and Literacy Partners.