The primary objective was to assess whether low-dose Interleukin-2 (IL-2) and 13-cis-retinoic acid (RA) could decrease serum vascular endothelial growth factor (VEGF) and improve the immune function of patients with advanced ovarian cancer (AOC) responsive to chemotherapy. The secondary end-point was to compare the response of these patients with that of a group of control patients, treated with standard care. Forty-four patients with AOC, responding to chemotherapy and with elevated serum levels of VEGF, were entered into the study from 04/98 to 12/02. After chemotherapy, patients received self-administered subcutaneous IL-2, 1.8x10(6) IU and oral RA, 0.5 mg/kg for 5 days/week for 2 consecutive cycles of 3 weeks, with a 1-week rest, for 1 year and with intermittent schedules for up to 5 years. Eighty-two well-matched controls were selected from a large cohort of patients of similar disease status, treated with standard therapies. A statistically significant decrease of VEGF was observed amongst the 44 evaluable patients. Lymphocyte NK counts and CD4+/CD8+ ratio improved with respect to both baseline values and controls. The progression-free survival (PFS) and overall survival (OS) curves showed a statistically significant improvement in IL-2/RA-treated patients. These preliminary data show that, after chemotherapy for AOC, the administration of low-dose subcutaneous IL-2 and oral RA is feasible, has low toxicity, is cost-effective and improves both PFS and OS.