Creatine kinase BB isoenzyme (CK-BB) is overexpressed in many tumor tissues, including ovarian cancer. Using a highly sensitive and specific immunofluorometric method, CK-BB levels in 89 primary ovarian cancer cytosolic extracts have been measured and the associations between CK-BB and clinicopathological features of ovarian cancer have been studied. It was found that CK-BB levels are higher in endometrioid cell carcinomas. No clear association was established between CK-BB levels and patient age, menopausal status, clinical stage, histological grade or size of residual tumor. CK-BB was not associated significantly with either disease-free or overall survival of the patients. Based on these data, it was concluded that there is no prognostic value of CK-BB in ovarian cancer. Drugs that target CK-dependent energy metabolism of tumor cells may not be selective in ovarian cancer therapy.