Pseudomembranous colitis (PMC) is a rare but potentially severe complication of antibiotic treatment, which is characterized by the proliferation of the bacterium Clostridium difficile in the colon. In this retrospective study, 48 cases of endoscopically confirmed PMC were included. The following variables were analysed: characteristics of the patients, antibiotics, clinical, biological and endoscopic features of PMC and its treatment. The antibiotic treatment was often ambulatory (83 per cent) for a broncho-pulmonary infection (42 per cent). In 90 per cent of the cases, the treatment included a -lactam, frequently amoxicillin with clavulanic acid, and in 25 per cent of the cases, a fluoroquinolone. The PMC generally occurred after more than 4 days of treatment and was associated with diarrhoea, abdominal pain, fever and rarely vomiting (23 per cent). The complications were hypokalaemia (37 per cent), renal failure (27 per cent) and/or hypoproteinaemia (50 per cent). Pseumembranes were found between the rectum and the left angle of the colon. All patients recovered after one week of oral treatment with metronidazole and/or vancomycin, often in association with Saccharomyces boulardii.