Morphology and ultrastructure of the metathoracic scent glands (MTG) of Graphosoma semi punctatum (Heteroptera: Pentatomidae) were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Extracts of the volatile fraction of the MTG secretions from male and female were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). In SEM investigations, MTG are composed of reservoir and a pair of glands located at the lateral site. Lateral glands connect to the reservoir with a duct. MTG open between the meso- and the metacoxae. These areas which have mushroom-like structures are called evaporation area. In TEM investigations, reservoir walls contain two types of cells. Generally, reservoir is lined by a single layer epithelial cells. These cells which have numerous organelles are named Type I cells. Type II cells are found only in a certain area of reservoir wall. These cells contain big secretory ducts lined by cuticular intima layer. Lateral glands which have two types of cells connected to the reservoir. Lateral glands which have secretory duct in their cytoplasm are lined by type I secretory cells. Type II cells have poor organelles. They are smaller than type I cells. In GC-MS investigations, MTG of each male and female of G. semipunctatum are very different in chemical coumpounds. In the MTG of females of G. semipunctatum, n-tridecane was determined maximum 44,97% and 3-Hexadecene was determined minimum 0,02% while in the males of G. semipunctatum n-tridecane was determined maximum 45,49% and 2-Dipentyl acetate was determined minimum 0,01%