Sister-chromatid exchanges (SCE) in peripheral blood lymphocytes and mutagenicity of urine (Ames test) were measured in a group of 21 nurses professionally handling antineoplastic drugs and in a group of 21 unexposed controls. No differences in SCE frequencies and in urinary mutagenic activity between exposed and unexposed groups were detected. A clear positive increase in urinary mutagenicity in the TA98 Salmonella strain was observed with increasing number of cigarettes smoked, whereas no evident influence of smoking on SCE was seen. Age, coffee and alcohol consumption did not show any detectable effect in the two tests.