Patulin is a mycotoxin produced by several species of Penicillium, Aspergillus and Byssochlamys. Patulin is a common contaminant of ripe apples used for the production of apple juice concentrates and is also present in other fruits, vegetables and food products. Patulin has been reported to have mutagenic, carcinogenic and teratogenic properties. Nevertheless, these properties are still a matter of debate. In this report, we further investigated the genotoxicity of patulin in mammalian cells by two different approaches. Firstly, we evaluated the induction of micronuclei in cytokinesis-blocked human lymphocytes, This approach is important because available data concerning the genetic toxicity of patulin in human cells is sparse. secondly, we chose an established model for patulin genotoxicity, i.e. the chromosomal aberration assay in V79 Chinese hamster cells, to clarify whether concomitant exposure to ascorbic acid with the mycotoxin modulates or not the clastogenicity of patulin. The results unequivocally show induction of DNA-damaged cells by patulin as assessed by both cytogenetic assays. In addition, an almost complete abolition of patulin (0.8 mu M) clastogenicity was observed in the presence of 80 mu M ascorbic acid (P < 0.05), showing that although a genetic risk is present, ascorbic acid could somehow partially modulate this problem.