The varying tumorbiological behaviour of ovarian carcinomas probably influences operability, response to chemotherapy, being one of the most relevant prognostic factors. Because it is believed that an activation of the epidermal growth factor/transforming growth factor alpha (EGF/TGF alpha) signal pathway could be involved, we analysed the expression of epidermal growth factor receptor (EGFR) and TGF alpha with molecular-chemical, biochemical and immunohistochemical methods in 42 ovarian carcinomas, 4 ovarian metastasis, 2 other malignant ovarian tumours, and in 25 nonmalignant tissues (ovary, myometrium). No major rearrangements or amplification of the EGFR or TGF alpha genes were found. In non-malignant tissues no strong EGFR or TGF alpha signals were detected. TGF alpha is mainly produced by the tumour cells as shown by immunohistochemistry. Four different high molecular weight forms (20-48 kD) were detected in malignant tissues by western blot analysis.