The neuron-specific enolase, gamma-enolase, is present at high concentrations in tissues of the nervous and neuroendocrine systems and at significant levels in other human tissues as detected by enzyme immunoassay. Its precise localization, however, has remained unclear. We report here the immunohistochemical localization of gamma-enolase in normal adult human tissues other than those of the nervous and neuroendocrine systems using direct and indirect enzyme-labeled antibody methods. The gamma-enolase was found in such smooth muscle cells as the media of aorta, fibromuscular tissue of the prostate, and the myometrium of the uterus, myoepithelial cells, the conducting system of heart, epithelial cells of loops of Henle, and macula densa cells of the kidney. It was also demonstrated in spermatogonia, lymphocytes, plasma cells, platelets, and megakaryocytes and in lesser amounts in bronchial epithelial cells and type II alveolar epithelial cells of the lung, and in secretory cells of the fallopian tube. The significance of its presence in these cells and the application of the gamma-enolase detection for diagnostic purposes in pathology are discussed.