This study assessed the extent and correlates of the practice of engaging in unprotected intercourse for extra money among commercial sex workers (CSWs) in Kinshasa, Democratic Republic of the Congo. We conducted a cross-sectional survey using a structured, interviewer-administered questionnaire among a convenience sample of 136 CSWs. More than one-quarter of CSWs (26.5%) engaged in unprotected intercourse for extra money. These CSWs charged about 3.5 times more for unprotected intercourse than for protected intercourse. Multivariate logistic regression showed that CSWs who engaged in unprotected intercourse for extra money were significantly more likely to live or work in non-downtown (lower socioeconomic) areas of Kinshasa (odds ratio [OR] = 3.07), to have at least one child less than six years of age (OR = 2.95), and to know other CSWs who engaged in the same practice (OR = 9.38). We hypothesize that desperate socioeconomic conditions combined with peer/social norms drive the practice of engaging in unprotected intercourse for extra money. Additional circumstances under which Kinshasa CSWs engaged in unprotected intercourse included intercourse with clients who tore their condoms to increase sexual pleasure (58.8% of CSWs), episodes of condom failure (56.8% of CSWs), and unprotected intercourse with regular noncommercial partners (only 5.3% of CSWs with noncommercial partners always used condoms with these partners).