Introduction - Administrative detention centers (CRA) house undocumented immigrants awaiting a decision regarding their continued detention or removal from the country. The purpose of this study was to assess the health of detainees. Methods - A prospective, systematic collection of health data over one year (September 24, 2008–September 23, 2009) from detainees at the Bobigny center (Seine-Saint-Denis) during their medical examinations. In-depth interviews and standardized questionnaires were administered to 100 individuals. Results - 1,733 out of 2,072 individuals (83%) were examined (median age: 31 years). Of the 100 individuals who completed the questionnaire and interview, only 37 (37%) perceived their physical and mental health as good. Among 1,675 individuals, 991 (59%) reported no medical history, 485 patients (29%) had a medical history, and 288 (17%) had a surgical history. Prescriptions were primarily for analgesics (2,550 out of 6,154 consultations, 41%), hypnotics (1,238, 20%), and anxiolytics (858, 14%). Five cases of hypertension and four cases of diabetes were identified. Conclusion - The frequency of multiple symptoms, anxiety, and sleep disorders may reflect the anxiety-inducing nature of detention and concerns related to deportation, or a pre-existing condition linked to social vulnerability. (R.A.)