1. The non-steroidal anti-inflammatory drugs (NSAID) are a group of drugs that possess both analgesic and anti-inflammatory properties. They are used to treat a variety of painful and inflammatory disorders such as postoperative pain, dental surgery, headache, acute and chronic musculoskeletal pain. 2. There is now substantial evidence that NSAID produce analgesia by inhibiting prostaglandin (PG) synthesis both in the peripheral and central nervous system. However, other mechanisms of action should also be considered. There is a multiplicity of mediators capable of producing pain, and NSAID may act both on the peripheral and central nervous system to modulate such mediators. There is a growing body of evidence suggesting that NSAID can exert an effect on specific G-protein dependent functions. 3. There is significant intra- and interpatient variability in the response to NSAID. Development of tolerance after multiple doses may provide an explanation for the unsatisfactory response to NSAID in some patients. 4. It has been suggested that the rate of decline of drug effect is characteristic of analgesia itself and indicates that an endogenous substance mediates the analgesic effect; possible candidates include serotonin. 5. NSAID remain an important therapeutic option in the management of pain.