Wilhelmina Behmenburg Cooper, 40, former top international model and head of her own modeling agency in New York and Los Angeles, died of cancer Saturday at Greenwich Hospital in Greenwich, Conn.

Born in Culenberg, The Netherlands, she started her modeling career in Chicago where her family had moved and her father was a butcher. Known professionally as Wilhelmina, she was tapped for her first modeling assignment with the Ford Agency in Chicago in 1958 when she accompanied a friend to an appointment to give her moral support.

Modeling success is often measured in magazine covers and Wilhelmina's record of 300 covers of Vogue magazine, reportedly has never been touched by another model. In fact, no one is expected to surpass it.

She was particularly proud of her most recent cover, Fortune Magazine on December 3, 1979. The cover story was on the modeling business.

According to Jerry Ford, husband and business partner of Eileen Ford; head of the Ford Agency, Wilhelmina was the outstanding model of the early 1960s.

"Her 'look' was 'the look' of the time," he said, referring to the reed-thin, high-cheekboned look of the 5-foot-11 Wilhelmina. "It was simply the 'look" that made her such a success," he said.

About the competition between the in magazine covers and Wilhelmina's "Even Wilhelmina would admit that we were a bigger company than she was," said Ford, who admitted that they were fierce compeitors.

In 1967 Wilhelmina opened Wilhelmina Models Inc. in New York with her husband Bruce Cooper, a former television producer. Since that time they have added a talent agency and opened a branch in Hollywood, called Wilhelmina West.

The agency represents models Patti Hansen, Shaun Casey, Julie Foster and Anne Marie Pohtano plus Pam Dawber of the "Mork and Mindy" television program. In total, the company represents about 300 models, according to an agency spokesperson.

Wilhelmina was always available to the young models for personal and professional guidance. "She always spent time in her office with the young models," said Bill Weinberg of the Wilhelmina agency. "She always found time to help them with all of their problems and always gave them help with their make-up."

In 1978 Simon and Schuster published her beauty book, "The New You."

She is survived by her husband, of Cos Cob, Conn., two children and her mother.