The structural organization of the lamina muscularis mucosae of the human esophagus was studied by light microscopy and scanning electron microscopy (SEM). The organization of the lamina muscularis mucosae varied considerably among the cervical, the thoracic, and the abdominal part of the esophagus. In the cervical part, the lamina muscularis mucosae was not well developed and only islets of the smooth muscle bundles were scattered within the connective tissue. In the thoracic part,the lamina muscularis mucosae consisted of several layers of smooth muscle bundles, individual muscle cells of which ran in a longitudinal direction. In the abdominal esophagus near the cardia, the muscular bundles in the lamina muscularis mucosae ran in various directions forming a reticular configuration. The differences in density and arrangement of the lamina muscularis mucosae are discussed in relation to the swallowing of food and submucosal invasion of esophageal cancer.