To investigate the etiology of nasal septal deviation, twenty-four fetal sinonasal specimens aged between 8-40 weeks of gestation were studied under light microscopy. Sixteen fetal heads aged between 32-40 weeks were examined using 2.7 mm 5 degrees Wolf endoscope. Five of 24 fetal sinonasal specimens were confirmed histopathologically to have deviated nasal septum. 1 of 16 fetal heads was considered to have nasal septal deviation. The existence of nasal septal deviation in fetuses was confirmed. To explain the embryogenesis, we suggested that maldevelopment of vomeropalatal complex is responsible for the formation of nasal septal deviation in fetuses.