The aim of the study was to determine whether international students have greater risk-taking behaviours that could lead to importing novel and resistant strains of sexually transmitted infections (STIs). We conducted a cross-sectional web-based survey of university students' sexual behaviour, alcohol and drug use, and self-reported diagnosis of STIs and compared these between British and international students. In all, 827 students completed the survey, of whom 123 (15%) were international students. International students were less likely to have ever drunk alcohol (95.4% versus 87.8%, P = 0.002) and used drugs (56.4% versus 41.5%, P = 0.002). International students were on average almost two years older at first intercourse (18.7 versus 17 years; P < 0.001). There were no differences in the number of sexual partners between national and international students. On a discriminant analysis model, international students were characterized by being older and from a non-white background, less likely to use cocaine, they drank alcohol less frequently and were more likely to have had unprotected intercourse with two or more partners in the previous year. In conclusion, international students tend to drink more moderately and use fewer recreational drugs than British students. However, they exhibit higher sexual risk behaviours that could lead to importing novel and resistant strains of STIs.