Recent findings have suggested that oxidative damage might contribute to the cytotoxicity and carcinogenicity of aflatoxin B1 (AFB1). Induction of oxidative stress also plays an important role in the toxicity of another mycotoxin, ochratoxin A (OTA). In the present study, the protective effect of cyanidin-3-O-β-glucopyranoside (C-3-G; an anthocyanin contained in oranges, blackberries, strawberries and cranberries) against AFB1- and OTA-induced cytotoxicity was investigated in a human hepatoma-derived cell line (Hep G2) and a human colonic adenocarcinoma cell line (CaCo-2). The ability of C-3-G to reduce the production of reactive oxygen species (ROS), the inhibition of protein and DNA synthesis and the apoptosis caused by the two mycotoxins was also investigated in both cell lines. Our experiments proved the significant cytoprotective effect of C-3-G in vitro against OTA- and AFB1-induced cell damage. In particular, 24 h of pretreatment with 50 μm-C-3-G inhibited the cytotoxicity of 10 μm-AFB1 (by 35 %) and of 10 μm-OTA (by 25 %) in Hep G2 cells (P<0·001) and of 10 μm-AFB1 (by 10 %, P<0·01) and of 10 μm-OTA (by 14 %, P<0·05) in CaCo-2 cells. Moreover, 50 μm-C-3-G attenuated ROS production induced by the two toxins in both cell lines (P<0·05). Inhibition of DNA and protein synthesis induced by the mycotoxins was counteracted by pretreatment with the antioxidant at 50 μm. Similarly, apoptotic cell death was prevented as demonstrated by a reduction of DNA fragmentation and inhibition of caspase-3 activation. The in vitro free-radical scavenging capacity of the anthocyanin was tested with the Briggs–Rauscher oscillating reaction. This system works at pH approximately 2. The results showed good scavenging power, in accordance with the observed inhibition of ROS production.