Pseudomembranous colitis (PMC), is characterized by acute onset, severe diarrhea, hypovolemic shock, toxic expansion of colon perforation, thrombus syndrome and without treatment in some cases leading to death of the patient. The paper describes a clinical case of pseudomembranous colitis in patients 35 years that developed on the background of the massive antibiotic therapy. The diagnosis was made only at autopsy. This case is unique, and dictates the need to inform doctors of practical health care of the complications of antibiotic therapy, such as pseudomembranous colitis.