The study was designed to assess the association between drug use and gonorrhoea in a UK setting and determine whether any differences identified could be explained by variations in sexual behaviour. A case control analysis was undertaken in a population of men and women presenting to an inner city sexually transmitted diseases clinic. The results were analysed using a multivariate model incorporating demographic and behavioural factors potentially associated with acquiring gonorrhoea. Infection with gonorrhoea was found to be associated with illicit drug use (odds ratio 1.8, 1.2-2.8) and the association became non-significant after controlling for sexual behaviour factors. Moderate alcohol use (<5 units/week) was associated with acquiring gonorrhoea but heavier use was not. Patients who used illicit drugs had more casual partners and more foreign partners than those with no history of drug use, but an increased numbers of foreign partners were not associated with a higher prevalence of gonorrhoea. It was concluded that drug use is associated with gonorrhoea in a UK setting. Specific sexual behaviours reported by drug users may increase their risk of gonorrhoea and provide potential targets for behavioural interventions.