Objectives To determine the effect of counselling on condom use by prostitutes. Design Cohort study. Setting Field-based study in The Gambia. Participants Thirty-one (12 HIV-positive and 19 HIV-negative) prostitutes. Interventions Post-test HIV counselling. Main outcome measures Levels of condom use. Results Overall, counselling had no effect on condom use. Conclusions Scarce resources should be directed towards providing condoms in bars rather than counselling.