|Abstract||It has been shown that during feeding the midgut epithelium of the human louse Pediculus humanus corporis consists of three types of cells: secretory, digestive, and reserve (regenerative) ones. According to the ultrastructural organization the secretory cells are subdivided into two regions--apical and basal. In the apical region of the secretory cells no microvilli are observed. The basal region contains mitochondria, ribosomes, rough endoplasmatic reticulum, microvesicular bodies and secretory granules. Three types of secretion of digestive enzymes (macroapocrine, microapocrine and merocrine ones) were found. The apical surface of the digestive cells is covered with microvilli; the cytoplasm of the digestive cells is filled with lipids and glycogen granules. Cells are lined with a homogeneous basal membrane.