Eighteen patients with suspected primary or recurrent ovarian carcinoma have been investigated in each case by the assay of serum levels of the antigen CA125, immunoscintigraphy using 131I-OC125 antibody and magnetic resonance imaging using a 0.15 Tesla system. The final diagnosis was confirmed by laparotomy or laparoscopy. Serum levels of CA125 ranged between 5 and 780 units/ml (normal range less than 35). Antibody images and MRI were truly positive in 11 patients, 2 of whom were subsequently found to have bowel tumours. MRI showed greater detail of smaller lesions whilst immunoscintigraphy was more suited to the detection of distant metastases. In 7 patients the antibody images were positive whilst the serum marker levels were normal. This pilot study provides a preliminary comparison of the more recent techniques currently being evaluated for the detection of ovarian carcinoma.