Four patients with recent antibiotic exposure suffered from diarrhea, abdominal pain and fever. Pseudomenbranous colitis was diagnosed by endoscopy and/or tissue biopsy. Culture of tissue specimens in 2 of 4 patients grew Clostridium difficile. All patients were treated with oral vancomycin 2 g daily. The symptoms relieved in 3-7 days. Follow-up endoscopic examination in 3 patients showed normal or resolution of lesions. One patient suffered from same symptoms after one course of therapy and relapse of pseudomenbranous colitis was proved by colonoscopy with biopsy. The patient was cured with vancomycin retreatment. Literature was reviewed and etiology, epidemiology, clinical feature, diagnosis, treatment, prognosis and prevention of pseudomenbranous colitis were discussed.