Twenty-six controlled prognostic evaluations of the adjuvant use of levamisole in cancer are reviewed. The results favor intermittent administration of levamisole in a dosage that is adapted to the patient's weight or body surface. Early treatment is indicated, but synchronous treatment with cytotoxic therapies is to be avoided. The best results have been achieved in advanced but still potentially curable patients. Major toxicity occurs very seldom and measures are suggested to further characterize the few patients who are at risk of developing allergic agranulocytosis, a potentially life-threatening side effect.