This study presents the oocyte development of Poecilimon ataturki unal, 1999 (Orthoptera, Tettigoniidae) with histology, morphology, and histochemistry by using a stereomicroscope, a light microscope, a scanning electron microscope, and a transmission electron microscope. The ovary in this species is a panoistic type which contains many ovarioles which consist of terminal filament, germarium, and vitellarium. Germarium is the region that has undifferentiated cells which generate the oocytes and follicular cells. In the vitellarium region, yolk granules start to cover the whole oocyte. In histochemical studies, to determine the content of the yolk granules, proteins, and carbohydrates in oocytes were treated with a bromophenol blue (BPB) method, a mercury bromophenol blue (mBPB) method, and a periodic acid Schiff (PAS) method, respectively. As a result of these methods, the yolk granules gave positive results in ovariole sections treated with the PAS and the BPB, while the mBPB staining was negative.