Hemorrhoidal disease is a common problem in general population and it affects our daily life. The major symptoms of hemorrhoids are anal bleeding and anal pain. Clinically, anal bleeding may lead to acute or chronic anemia which would make the hypoxia worse and decrease the G tolerance. In addition, the stress caused by anal pain may affect the performance of the pilots. Therefore, we should pay much attention to the effects of hemorrhoids to the health of aircrews and the flying safety.