The expression of different genes potentially involved in DNA repair and in cell responses to chemotherapy was evaluated in 33 previously untreated ovarian cancer patients. In biopsies of the same patients the expression of repair genesO6-methylguanine DNA methyltransferase (MGMT), 3-methyladenine DNA glycosylase (MAG), ERCC1, MDR-1, DNA topoisomerase I, DNA topoisomerase IIα, and glutathioneS-transferase-π (GST-π) was assessed by Northern blot analysis. No direct statistical correlation was found between the expression of these genes and the response to chemotherapy (mainly platinum-based with or without doxorubicin and cyclophosphamide). Univariate analysis showed a weak negative correlation (P= 0.037) between the expression of ERCC1 and mortality, whereas no statistically significant correlation was found for other parameters. The MDR-1 gene encoding for the P-glycoprotein P-170 was mostly undetectable in these patients (as assessed by Northern blotting), whereas relatively high levels of MAG and MGMT were found in the majority of patients. A statistically significant correlation was found between the expression of DNA topoisomerase I and the expression of either ERCC1 (P= 0.0026) or GST-π (P= 0.0279).