Serial immunologic tests (active E-rosettes = T-Ea; total E-rosettes = T-Et; total lymphocytes and null cells) were performed every 3 months for 5 years on 113 melanoma patients. A significant reduction in absolute T-Ea, T-Et, null cells, and total lymphocytes was noted in the patients who died, by comparison with those who are still alive. The latter presented a significant reduction in absolute T-Et only, plus a significant increase in null cells when compared with normals. The 38 patients without metastases, at the end of the study, presented a reduction in T-Et and an increase in null cells compared with the normals, while the 75 patients with metastases presented a reduction in T-Et, null cells and total lymphocytes when compared with the patients without metastases and a reduction in T-Ea, T-Et, and total lymphocytes when compared with the normals. Null cells show a linear decrease in patients who died and a linear increase in those who survived. A total of 80.2% of patients with a fall in T-Et displayed metastases usually within 2 to 10 months (mean, 6.8). Patients with normal T-Ea, T-Et, and total lymphocyte values showed a significant prolonged survival when compared to those with lower values. In addition, survival seemed to be always a function of immunologic test values, irrespective of the tumor site.