Epidemiological evidence indicates that plant derived flavonoids and other phenolic antioxidants protect against heart disease and cancer. In the current investigation utilizing human oral squamous carcinoma cell line (SCC-25), we have evaluated the potency of three different plant phenolics, viz., curcumin, genistein and quercetin in comparison with that of cisplatin on growth and proliferation of SCC-25. Test agents were dissolved in DMSO and incubated in triplicates in 25 cm2 flasks in DMEM- HAM's F-12 (50:50)supplemented with 10% calf serum and antibiotics in an atmosphere 5% CO2 in air for 72 hours cell growth was determined by counting the number of cells in a hemocytometer. Cell proliferation was determined by measuring DNA synthesis by the incorporation of [3H]-thymidine in nuclear DNA. Cisplatin (0.1, 1.0, 10.0 microM) and curcumin (0.1, 1.0, 10.0 microM) induced significant dose-dependent inhibition in both cell growth as well as cell proliferation. Genistein and quercetin (1.0, 10.0, 100.0 microM) had biphasic effect, depending on their concentrations, on cell growth as well as cell proliferation. Based on these findings, it is concluded that curcumin is considerably more potent than genistein and quercetin, but cisplatin is five fold more potent than curcumin in inhibition of growth and DNA synthesis in SCC-25.