There are five main causes of blood in the toilet for men: First, hemorrhoids are the most common cause of blood in the stool, manifesting mainly as blood dripping from the anus after the stool, stool mixed with fresh blood, not accompanied by severe pain in the anus. Second, anal fissure, common in patients with a long history of constipation, clinical manifestations of blood dripping after the stool, accompanied by severe anal pain, the formation of anterior sentinel hemorrhoids. Third, rectal adenoma and hyperplastic polyp, no obvious symptoms, when the adenoma or polyp surface mucosal blood vessels rupture can cause blood in the stool, the bleeding volume is small. Fourth, upper gastrointestinal bleeding, mostly gastroduodenal ulcer bleeding, no blood in the stool appears, mostly black stool, may be accompanied by regular abdominal pain. Fifth, rectal malignant tumor, early often no obvious clinical symptoms, when the disease progresses to advanced stage, can appear blood in the stool, black stool, accompanied by changes in stool properties.