A tumour-associated radiolabelled monoclonal antibody (Mab) 131I-OC 125 F(ab')2 was used to investigate 27 patients 2 weeks after their last chemotherapy regimen and prior to second-look surgery for ovarian cancer. We did compare the radioimmunoscintigraphy (RIS) findings with the CT scan results and the second-look operation data. In 23 out of 27 cases the RIS results correlated with the operation findings, while there were four false-negative results. Computed tomography (CT) scans correlated in 17 out of 23 cases with the operative findings, while there were six false-negative results. We concluded that RIS is more specific in detecting the tumour site within the pelvis, while CT scan is superior in detecting liver metastases.