The aim of this study was to determine the usefulness of radioimmunoscintigraphy (RIS) with monoclonal antibodies (MAb) to detect primary ocular melanoma and its relapses and metastases. The authors studied nineteen patients (9 men and 10 women), aged 24 to 74 who were suspected of having ocular pigmented tumors by means of RIS. The authors used F(ad)2-fragments of monoclonal antibodies against high molecular weight-melanoma associated antigen, labeled with Tc-99m (activity 370-555 MBq). Planar and SPECT imaging were performed at 6, 12, and 24 hours. The sensitivity of the method was 78.6%; the specificity was 100%; and the accuracy was 84.2%. The results obtained suggest that RIS is a highly specific and sensitive technique in the differential diagnosis of malignant ocular melanoma.