A prospective pilot study was performed in order to determine the efficacy of 111InCyt103 (ONCOScintr CR/OV) in the detection of the presence and location, or absence of disease among patients with epithelial ovarian cancer who demonstrated no clinical or biochemical (Ca 125: < 35 mu/ml) evidence of disease at the end of first-line therapy. Among 15 patients who underwent second-look laparotomy, the overall accuracy of the test was 60%. The test demonstrated a sensitivity of 62.5% and a specificity of 57.1%. The predictive value of a positive test was 62.5% and of a negative test was 57.1%. The correct location of disease was predicted in 57% of patients with macroscopically appreciable tumors. ONCOScintr CR/OV offers little appreciable advantage over current modalities in discriminating between the presence or absence of disease among patients with epithelial ovarian cancer who demonstrate no clinical evidence of disease at the end of first-line therapy.