Thirteen saponins were isolated and identified from Calendula officinalis, C. arvensis and Hedera helix. Mutagenic and antimutagenic activities of these products were investigated using a modified liquid incubation technique of the Salmonella/microsomal assay. The Salmonella tester strain TA98 +/- S9 mix was used. Screening of the antimutagenic activity was performed with a known promutagen: benzo-[a]pyrene (BaP) and a mutagenic urine concentrate from a smoker (SU). Antimutagenic activities were also compared with the activity of chlorophyllin. All the saponins were found to be non-toxic and non-mutagenic for doses of 400 micrograms. Chlorophyllin inhibited the mutagenic activities of BaP (1 microgram) and SU (5 microliters) in a dose-dependent manner. The four saponins from C. arvensis and the three saponins from H. helix showed antimutagenic activity against BaP (1 microgram) and SU (5 microliters) with a dose-response relationship. The possible mechanism of the antimutagenic activity of saponins is discussed.