Introduction – Crack use is associated with a significant deterioration in users’ social and mental health. The objective of this study is to estimate the prevalence of psychiatric disorders among crack users in Paris. Materials and Methods – Users of psychoactive substances were recruited using respondent-driven sampling. They had to be over 18 years of age and provide a urine sample confirming drug use. Only data from those reporting crack use within the past 30 days were analyzed. The prevalence of psychiatric disorders was estimated in two stages: initial screening using a simplified psychiatric screening questionnaire administered by trained peers; followed by referral to a healthcare provider for completion of a standardized psychiatric diagnostic questionnaire (Mini 5.0), followed by an evaluation by a psychiatrist when a disorder was diagnosed. Results – Among the 1,202 participating clients, 485 had used crack in the past 30 days and had undergone the screening process. Among them, 38% of participants had at least one psychiatric disorder and 20% had multiple disorders. The adjusted prevalence of at least one psychiatric disorder was 43.5%. Women (10% of the sample) exhibited significantly poorer mental health despite a less precarious social situation. Conclusion – Although likely underestimated, the prevalence rates found are high and alarming among women. Adjustments to the care system are undoubtedly necessary.