In this study, ultrastructure of digestive canal of Graphosoma lineatum (Linnaeus, 1758) (Heteroptera, Pentatomidae) was examined with the use of light, scanning (SEM) and transmission electron microscope (TEM). The digestive canal of G. lineatum consists of three distinct regions: Foregut, midgut and hindgut. The foregut and hindgut are very short. The midgut is longer and differentiated into three distinct portions: anterior, median, posterior. The anterior region is similar to a wide elongated sac, the median region is narrower than the other regions of midgut and tubular in shape, the posterior region is short and dilated. There are two pairs of Malpighian tubules at the junction of midgut and hindgut. The alimentary canal of G. lineatum is generally similar to that of the digestive system of other Heteroptera. The epithelial cells of the foregut are cubically arranged as a single layer. In the SEM and TEM images, the foregut is seen to be surrounded by a layer of longitudinal muscle and inner surface is formed by cell groups located over a folded basal lamina. The surface of midgut is composed of a single layer of cylindrical cells surrounded by a layer of inner circular and outer longitudinal muscles. The hindgut is composed of an extremely thin epithelial cell layer. It appears wrinkled, but does not contain microvilli.