Patulin (PAT) is a fungal secondary metabolite commonly present in apples and apple products. In the present study, PAT was evaluated for its genotoxic, cytotoxic and cytostatic effects to human peripheral blood lymphocytes by using the cytokinesis-block micronucleus cytome (CBMN Cyt) assay. Lymphocyte cultures were treated with PAT at the following concentrations, 0.1, 0.3, 0.5, 1.0, 2.5, 5.0, and 7.5 mu M, as well as 0.5 mu M mitomycin c (MMC) as a positive control and dimethyl sulfoxide (DMSO) as a vehicle control. PAT was found to induce nucleoplasmic bridges (NPBs) at 5.0 and 7.5 mu M concentrations (P<0.05), apoptotic cells at 0.1, 1.0, 5.0 mu M (P< 0.05), 7.5 mu M concentrations (P< 0.01) and necrotic cells at 0.3 and 2.5 mu M (P< 0.05), 5.0 and 7.5 mu M (P < 0.01) concentrations in human lymphocytes. The 2.5, 5.0, and 7.5 mu M PAT concentrations also led to a clear decrease in the nuclear division index (NDI) (P< 0.05). PAT caused a significant dose-dependent increase in the number cells of NPBs, in the frequency of apoptotic and necrotic cells, and a significant dose-dependent decrease in the NDI values in lymphocytes. These results indicate that PAT at high concentrations is genotoxic, cytotoxic and cytostatic in cultured human lymphocytes.