Data was analyzed from 92 patients > 5 years after intraperitoneal (IP) radionuclide therapy (RIT) with (90)Y- or (177)Lu-CC49 to determine prognostic factors. Patients had CC49 antibody-reactive ovarian cancer confined to the abdominal cavity after primary debulking and chemotherapy. The first 27 patients received IP (177)Lu-CC49 alone; the remainder received Interferon (IFN), to increase the expression of the tumor-associated glycoprotein-72 (TAG-72) antigen, +/- IP paclitaxel (25-100 mg/m(2)) 2 days before RIT. Factors assessed by univariate (and some multivariate) analysis included age, race, body size, interval between initial diagnosis and RIT, interval between 2nd look surgery and RIT, (90)Y versus (177)Lu, MBq dose, paclitaxel dose, grade of tumor, extent of initial surgery, size of disease deposits prior to RIT, intensity of TAG reactivity, the addition of unlabeled antibody, and the development of human anti-mouse antibody and/or serum sickness after murine antibody. A statistically significant improvement in progression-free survival (p ≤ 0.05) was noted for less bulky disease and younger age. Administration of paclitaxel plus IFN, an immune response, and use of (90)Y showed a favorable nonsignificant trend. Dose escalation of radionuclide did not change risk of progression; thus, this therapy may have therapeutic efficacy at modest dose levels.