Background: in 1990, a national survey on adolescent sexuality showed that Turkish/Moroccan students were at special risk for sexually transmitted diseases. In 1995 the study was repeated. This article describes trends in the safe sex knowledge and sexual behaviour of Turkish/Moroccan students. The results are also seen in relation to those of Dutch students. Methods: data were collected from representative samples of students aged 11–18 years old in 1990 and in 1995, using structured questionnaires. Results: knowledge about AIDS among Turkish/Moroccan students increased. Boys became more permissive in their sexual attitudes, though the proportion of boys with coital experience did not change. Condom use among boys increased from 49 to 75%. The differences in sexual attitudes and behaviour between Turkish/Moroccan boys and girls increased. The Turkish/Moroccan boys became more similar to their Dutch counterparts, while the Turkish/Moroccan girls did not. Conclusions: these results suggest that safe sex education may have advantageous effects on Turkish/Moroccan adolescents' risk of sexually transmitted diseases.