Introduction - The objective of this study is to assess the prevalence of current use of legal drugs (alcohol and tobacco) and illicit drugs in the French civilian maritime sector based on reports from a sample of seafarers. Method - The data analyzed were collected from 1,928 seafarers through a stratified survey. The questionnaires were administered to seafarers during their annual medical examination with occupational physicians and nurses from the Seafarers’ Health Service. Testing for recent cannabis use was conducted via a urine test. Results - The prevalence of current smokers among seafarers is estimated at 44% for men and 37% for women. Approximately 11% of men drink alcohol daily. Cannabis use has been tried by 46% of seafarers, and 16% had smoked it in the month prior to the survey. Use of other drugs is estimated at 15%. Alcohol, tobacco, and cannabis use among men varies by age. Conclusion - French fishing and merchant seafarers constitute a population at risk in terms of public health. High prevalence rates of psychoactive substance use are observed compared to the general French population. Given the hazardous nature of the work, it seems important that young seafarers be aware of the addictions these psychoactive substances can cause. (R.A.)