BACKGROUND: A beriberi outbreak occurred in the Maison d'Arrêt et de Correction d'Abidjan (MACA), a detention center in Abidjan, Côte d'Ivoire, between October 2002 and April 2003. OBJECTIVE: A retrospective investigation was conducted to document the outbreak in April 2003. METHODS: A descriptive analysis and a case-control study were performed. A probable case patient was defined as a person detained in the center between October 2002 and April 2003 with at least two of the following symptoms: bilateral leg edema, dyspnea, positive squat test, motor deficiencies, and paresthesia. A definite case patient was defined as a probable case patient who showed clinical improvement under thiamin treatment. RESULTS: Of 712 cases reported, 115 (16%) were probable and 597 (84%) were definite. The overall attack rate was 14.1%, and the case fatality rate was 1.0% (7/712). The highest attack rate was reported in the building housing prisoners with long-term sentences (16.9%). All patients were male, and the mean age was 28 years. During the period studied, the penal ration provided a fifth of the quantity of thiamin recommended by international standards. After adjustment for potential confounders, a history of cholera infection (adjusted odds ratio [OR(a)], 12.9; 95% confidence interval [CI], 2.9 to 54.1) and incarceration in the building for severe penalties (OR(a), 4.8; 95% CI, 1.3 to 18.5) were associated with the disease. CONCLUSIONS: Beriberi has been underreported among prisoners. Further attention should be given to its risk factors, especially a history of acute diarrhea. Systematic food supplementation with vitamins and micronutrients should be discussed when the penal ration does not provide the necessary nutrient intake recommended according to international standards.