In vitro and in vivo effects of ginsenoside Rh2 on human ovarian tumor growth were examined by using a cell line (HRA) derived from ascites of a patient with serous cystadenocarcinoma of the ovary. The HRA cell proliferation in vitro was inhibited in a dose-dependent manner with dosages of 10-100 microM of ginsenoside RH2. DNA, RNA and protein synthesis by the HRA cells was inhibited in a dose-dependent manner at more than 15 microM of ginsenoside RH2. However, the growth of HRA cells transplanted in nude mice was not significantly inhibited by ginsenoside RH2. On the contrary, when cisplatin was administered together with 10 microM (but not 1 microM or 100 microM) ginsenoside RH2, the tumor growth was significantly inhibited 31 days after inoculation and the survival was also significantly prolonged, compared with not only the untreated group but also the groups given cisplatin alone or ginsenoside RH2 alone. This indicates synergistic effects between cisplatin and ginsenoside RH2. From monitoring of body weight and hematocrit, concentrations of ginsenoside RH2 used in this study did not seem to cause any adverse effect.