Non-steroidal anti-inflammatory drugs (NSAID) belong to the most commonly used drugs worldwide. NSAIDs can cause serious side effects to the gastrointestinal tract. During NSAIDs treatment 10–12 % patients suffer from dyspepsia. Up to 1 % patients develop severe gastrointestinal complications (ulcer, bleeding, perforation). Any part of gastrointestinal tract could be affected. In oesophagus, NSAIDs can cause oesophagitis or fibrous stricture. NSAID gastropathy can be detected in 40 % patients chronically treated with NSAIDs. NSAIDs toxic injury to small and large bowel is frequent but only seldom properly recognised. Serious hepatic lesions are rare. There is no fully reliable and sure prophylaxis or treatment of NSAIDs impairment of to the gastrointestinal tract. Rate of side effects can be reduced by reasonable prescriptions and by primary and secondary prophylaxis. Low rate of side effects is associated with the use of pro-drugs (compound is metabolised to an active substance after absorption from the gastrointestinal tract). New promising drugs were developed with dual action (5-lipoxygenase- and COX-inhibition) and NSAID releasing NO (nitronaproxen, nitrophenac). Specific COX-2 inhibitors (coxibes) provide comparable anti-inflammatory and analgesic effect but the risk of serious side effects to the gastrointestinal tract is significantly lower (when compared with non-specific NSAIDs). Beside harmful effects, NSAIDs are powerful tool in chemoprevention of colorectal cancer.

        Key words: non-steroidal anti-inflammatory drugs, NSAID, side effects, gastrointestinal tract.