Sixteen malignant cancer patients (seven melanoma, three colon, three lung, and three other) who received tumor vaccine therapy--14 autologous and two allogeneic--were studied for T-cell phenotyping changes. Blood samples were obtained prior to therapy, and also at various time intervals following the therapy. A consistent and reproducible elevation of T3 and T4 subsets, as tested on day 21 after the therapy, was observed in 12 patients. The mean percentages of T3 and T4 fractions before and after (21 days) the treatment were 63.8 versus 75.9% (p less than 0.002) and 44.4 versus 57.4% (p less than 0.001), respectively. Kinetic studies of absolute values of three melanoma patients also showed augmentation of T3 and T4 cells following each tumor vaccine. The lymphatic infusion of tumor vaccine did not cause any toxicity, particularly lymphadenopathy. We believe this is the first report demonstrating augmentation of T4 (helper/inducer) cells with tumor cell vaccine therapy.