DES Action Canada was founded in Montreal in 1982 by Harriet Simand and her mother Shirley, only a few months after she was diagnosed with a rare cancer linked to the drug diethylstilbestrol (or DES), that had been prescribed to her mother during her pregnancy twenty years earlier.

Under the sponsorship of the McGill University Cancer Centre, the Simands were awarded a $20,000 grant from Health and Welfare Canada to set up DES Action Canada in the basement of their home in Montreal's Notre-Dame-de-Grâce district. In 1983, Health and Welfare gave DES Action its first health promotion grant of $72,000 and the National office was established on Monkland Avenue in Montreal, information pamphlets were printed, the DES Action Newsletter was created and a physician referral list was developed. As the Simands continued their outreach work and as the media continued to cover the DES story, several DES Action groups were set up across the country. By 1999, DES Action Canada had grown to have 11 volunteer chapters across Canada.

Today, besides the rare reproductive system cancer that strikes a small number of DES daughters, DES has been linked to fertility problems in both the daughters and sons and breast cancer in DES mothers. Recent scientific research, in 2000 and 2001, suggests that grandsons and granddaughters of women prescribed DES - the third generation of DES-exposed people - may have an increased risk of developing cancer of the reproductive system. A lesson hard-learned, the DES tragedy encompasses public policy issues such as drug testing, company product liability, physician responsibility, and consumer health education, areas in which DES Action has developed expertise. In recent years, DES Action Canada has also developed expertise in the area of DES and its link to endocrine disrupters in the environment. DES Action remains the only organization in Canada working to raise public awareness of the DES health risks.