The numbers and the distribution of T-lymphocyte subpopulations in lymph node granulomas from 11 patients with sarcoidosis were studied in cryostat sections by an immunoperoxidase technique. Greater numbers of helper T lymphocytes (Leu-3+) were found at the periphery than in the central portion of the same granuloma. Most of the suppressor T lymphocytes (OKT8+) were present at the periphery of the granulomas. In addition, the Leu-3a/OKT8 ratio varied from 0.7 to 1.8 in the outer compartment, while in the central portion of the granuloma much higher values (3 to 20) were found. These different distribution patterns of T-lymphocyte subsets provide evidence for two different compartments with different immune reactions in sarcoid granulomas.