The oncogene specific mRNA of c-erbB-2 was detected by the S1 nuclease protection assay in 95 ovarian cancer specimens. In 79 primary carcinomas, we found 16 (20%) with strong expression, 13 (17%) with weak expression, 4 (5%) with very weak expression, and 46 (58%) with no expression. In 3 of 16 recurrencies (19%) a strong expression of c-erbB-2 mRNA was detected, in 2 (12%) weak expression was detected, and in 11 (69%) no expression of c-erbB-2 mRNA was detected. Kaplan-Meier analysis revealed no significant association between strong expression of c-erbB-2 mRNA and survival of the 79 patients with primary cancer. However, in the subgroup of patients with FIGO (International Federation of Gynecology and Obstetrics) stages III and IV (n = 60) a shorter median survival time (12 months) was obtained for patients with strong c-erbB-2 mRNA expression compared to patients with no, very weak, and weak c-erbB-2 mRNA expression (25 months, P = 0.04). In addition, strong expression of c-erbB-2 mRNA did not depend on histologic grade, histologic type, and FIGO stage. Adverse prognostic factors include histologic type (serous carcinoma), high grade, high stage (FIGO stages III and IV), and residual of tumor after surgery. From our results we conclude that for all patients (FIGO stages I-IV) strong expression of c-erbB-2 mRNA is not a prognostic parameter, but in the subpopulation of patients with FIGO stage III and IV only, an association between strong c-erbB-2 mRNA expression and shorter median survival time was found, although statistical significance was weak (P = 0.04).