This study examined patterns of alcohol use and its association with unsafe sex and related sequelae among female sex workers in Mombasa, Kenya. A community-based cross-sectional study was conducted using snowball sampling. Binge drinkers (> or =5 alcoholic drinks on > or =1 occasion in the previous month) were compared with non-binge drinkers. Of 719 participants, 22.4% were lifetime-alcohol abstainers, 44.7% non-binge and 33.0% binge drinkers. Compared with non-binge drinkers, binge drinkers were more likely to report unprotected sex (adjusted odds ratio (AOR)=1.59, 95% confidence interval [CI]=1.00-2.53; P=0.047) and sexual violence (AOR=1.85, 95% CI=1.27-2.71; P=0.001) and to have either syphilis, Neisseria gonorrhoeae or Trichomonas vaginalis infection (AOR=1.56, 95% CI=1.00-2.41; P=0.048). HIV prevalence was higher among women having ever drunk (39.9%) than lifetime abstainers (23.2%; P<0.001), but was not associated with drinking patterns. Interventions are needed to assist female sex workers adopt safer drinking patterns. Investigation is needed for the effectiveness of such interventions in reducing unprotected sex, sexual violence and sexually transmitted infections.