Telomerase activity and its subunits (hTERC, hTERT mRNA) were evaluated in ovarian tumours in relation to the expression of p53, c-Myc and estrogen receptor (ER). Furthermore, relations between telomerase activity, hTERC and hTERT with known clinicopathologic prognostic factors and survival in patients with malignant tumours was investigated. Telomerase activity was determined with TRAP, hTERC and hTERT with RT-PCR, while p53, c-Myc and ER expression with immunohistochemistry. Telomerase activity and hTERT mRNA were more frequently observed in malignant ovarian tumours compared to borderline and benign tumours, whereas hTERC was present in all tumour types. p53 and c-Myc were more frequently detected in malignant compared to borderline and benign tumours. Telomerase activity was positively related to hTERT mRNA, p53 and c-Myc expression, but not to hTERC and ER expression. In malignant tumours, hTERC levels were related to tumour stage, while telomerase activity and hTERT mRNA expression were not related to any clinicopathologic feature. Tumour stage, differentiation grade, residual tumour after first laparotomy and presence of ascites were related to (progression free) survival, whereas telomerase activity or its subunits were not. In conclusion, these data suggest that p53 expression (e.g. p53 mutation) as well as c-Myc expression may have a role in regulation of telomerase activity in ovarian tumours.