Recent reports suggest that recombinant interleukin-2 may be effective in the treatment of cancer patients with low tumor burden. Considering the poor long-term survival, 11 ovarian cancer patients with minimal residual disease at second-look have so far been selected for rIL-2 intravenous continuous infusion therapy: two induction courses (3 x 10(6) U/m2/day: 120 h + 108 h) followed by three maintenance courses (3 x 10(6) U/m2/day: 120 h) and third-look laparotomy. At present, three patients are still on treatment, three have completed it, and five have discontinued treatment. Sixty-seven per cent of the planned dose was administered in 49 cycles of which 42 (86%) required dose modifications due to hypotension (greater than or equal to grade III) and nephrotoxicity (greater than grade I). CNS and GI toxicity, allergies and fever, even though requiring dose modifications in a few cases, significantly affected patient compliance. The rebound lymphocytosis was clearly dose-related and a significant percentage increase after rIL-2 was detected only for IL-2 receptor positive cells. To date, four patients are evaluable for response after a median follow-up of 7 months, two progressed during the maintenance period, while one CR and one progression were detected in the two patients so far submitted to third-look laparotomy.