In an attempt to ameliorate the chemotherapy associated normal cell toxicity, in this study a known antioxidant, grape seed proanthocyanidin extract (GSPE) using Chang liver cells has been used. Chang liver cells were treated in vitro with idarubicin (Ida) (30 nM) and 4-hydroxyperoxycyclophosphamide (4-HC) (1 microg/ml) with or without proanthocyanidin (25 microg/ml). The cells were grown in vitro and the growth rate of the cells were determined using MTT assay. The results showed that the GSPE decreased growth inhibitory effects of Ida and 4-HC on Chang liver cells in vitro. Since these chemotherapeutic agents are known to induce apoptosis in the target cells, these cells were also analyzed for presence of apoptotic cells using flow cytometry. The GSPE decreased the number of apoptotic cell population induced by either chemotherapy. In an attempt to determine the mechanisms of ameliorating effects of proanthocyanidin, the expression of apoptosis/cell cycle/growth related genes, Bcl-2, p53 and c-myc was determined in the treated and control cells using Western blotting or reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. There was an increased expression of Bcl-2 in the cells treated with GSPE. However, there was a significant decrease in the expression of other cell cycle related genes such as p53 and c-myc in these cells following treatment with GSPE. Thus, these results indicate that proanthocyanidin can be a potential candidate to ameliorate the toxic effects associated with chemotherapeutic agents used in treatment of cancer.