Non-steroidal anti-inflammatory drugs (NSAIDs) may adversely affect the colon, either by causing a non-specific colitis or by exacerbating a preexisting colonic disease. Patients with NSAID-induced colitis present with bloody diarrhoea, weight loss, iron deficiency anaemia and sometimes abdominal pain. Colonoscopy may be normal or may show inflammation, ulceration or diaphragm-like stricture. Histology often concludes to non-specific colitis. NSAIDs may cause perforation or bleeding of colonic diverticula, may cause relapse to inflammatory bowel disease and may exacerbate bleeding of colonic angiodysplasia. Pathogenesis of NSAID-induced colitis is still controversial. Local and/or systemic effects of NSAIDs on mucosal cells might lead to an increased intestinal permeability, which is a prerequisite for colitis. Treatment of NSAID-induced colitis should be to discontinue the drug, or at least, to reduce the dose as much as possible. Sulphasalazine and Metronidazole have been successfully used in few studies. Surgery is often indicated in case of life threatening complications or untractable symptoms.