Antonio Lopez, a fashion illustrator whose drawings appeared frequently in Vogue, Harper's Bazaar, Elle, Interview and The New York Times and whose works were exhibited in galleries all over the world, died of AIDS yesterday morning in the U.C.L.A. Medical Center in Los Angeles. He was 44 years old.

Mr. Lopez, who lived in New York, had been in California for two weeks for an exhibition of his fashion drawings and personality portraits at the Robert Berman Gallery in Santa Monica. An exhibition of his drawings is also currently taking place in Munich, West Germany. He worked with a variety of materials including pencil, pen and ink, charcoal, watercolors and Polaroid film. He signed his work simply ''Antonio.''

An artist whose constantly changing but always flamboyant style has influenced the work of other fashion illustrators since the 1960's, Mr. Lopez also designed advertising campaigns in many parts of the world, including a trend-setting series of advertisements for Bloomingdale's in the last decade. Drawing at Two

A native of Puerto Rico, he came to New York City as a child. He once recalled that he had started drawing at the age of 2, sketching dresses from fabric his mother gave him. While a student at the Fashion Institute of Technology, he went to Women's Wear Daily, the trade publication, as part of a work-study program, where his talent was immediately recognized. The paper put him on staff and he left school.

In the early 1960's he began to freelance for fashion magazines, where his portraits of models such as Jerry Hall, Jessica Lange and Grace Jones enhanced their careers. Many of these portraits were collected in ''Antonio's Girls,'' a book published in 1982.

In 1969 he moved to Paris, where he and Karl Lagerfeld, the designer, ran a sort of salon for models and fashion personalities. He stayed there for seven years, during which time he introduced many facets of American pop culture to the French. Taught Workshops

He strayed from the realm of fashion in ''Antonio's Tales From the Thousand and One Nights,'' a book containing sensuous color illustrations and line drawings that was published in 1985 by Stewart, Tabori & Chang. Up until the time of his death, he had been working on a compilation of his fashion drawings to be called ''25 Years of Fashion'' that is scheduled for publication early in 1988. His long-time partner, Juan Ramos, plans to finish the book, to be published by Stewart, Tabori & Chang.

In the last 10 years, Mr. Lopez became interested in education and devoted much of his time to giving lectures and workshops to students of fashion illustration in many parts of the country and in the Dominican Republic.

He is survived by his mother, Maria Luisa Cruz; his father, Francisco Lopez, and two brothers, Roberto and Herbert Lopez, all of Puerto Rico. His body will be cremated and the ashes taken to Puerto Rico. There will be a memorial service sometime later in New York.

Photo of Antonio Lopez (Matthew Olszak)