We report on the cellular composition of the cutaneous lesions of 38 leprosy patients prior to and after 12-18 months of chemotherapy. All of the patients with tuberculoid (TT) disease had OKT4/OKT8 ratios that exceeded 1.0. In the indeterminate patients, the ratio varied depending upon the immune status of the individual. A low ratio of OKT4/OKT8 cells (0.25) was found in the LL patients as previously reported. The low ratio of OKT4/OKT8 in the lesions of lepromatous patients did not undergo significant changes after treatment in spite of a marked reduction in the number of intracellular bacilli.