Dorsal and ventral epithelium of leech, Whitemenia edentula, were observed, using both light and electron-microscope. Results are as follows. Epithelia are composed of simple columnar or irregularly-shaped epithelium, the transveral folds were seen in the cross-sectioned dorsal and ventral epithelia, but only longitudinal folds(depth $500{mu}m$, width $350{mu}m$) were discovered in the ventral epithelium. As to muscular tissue under the dorsal epithelium of Whitemenia edentula, that of longitudinal muscle layer is thicker and more developed than that of circular muscle layer. Seven gland cells (type-A, B, C, D, E, F and H cells) and one pigment cell (type-G cell) were discovered in the whitemenia edentula. Those were identified as three kinds of the neutral mucopolysaccharide granoles (type-A, B and F cells), two kinds of acidic mucopolysaccharide granules (type-C and D cells), and two kinds of non-reactive granules respectively (type-E and F cells). The glanules of the type-A and type-B gland cells ae electronly high-dense, and surrounded by the muscular tissue. As to the distribution of gland cells, the type-A, type-B, type-C, type-D, type-I and type-H gland cells were discovered only between the connective tissue and the circular muscle layer, while type-F gland cells were discovered only between tile circular muscle layer and the longitudinal muscle layer.