The results of a randomized trial, stratified according to age and stage of disease, in 140 patients with ovarian cancer are presented. The drug, levamisole, or a placebo was given as adjuvant to cytotoxic chemotherapy for 12 months after maximal surgical reduction of tumor. Because of severe side effects, levamisole treatment was discontinued in 8 of 69 patients (marked neutropenia in 5, severe skin rashes in 3). There were no significant differences in the survival curve and mean duration of survival between levamisole-treated and placebo-treated groups during the 4 years of follow-up, except for patients with Stage II disease. Among these latter patients, the survival rate became progressively much lower in the levamisole-treated group and the difference reached statistical significance after the second year of follow-up (P less than 0.01). In view of the inconclusive evidence that levamisole provides a beneficial effect (in fact, there is concern of a deleterious effect) and the serious side effects, the drug should not be used in patients with ovarian cancer.