Tramadol hydrochloride is a centrally-acting, synthetic analgesic with a dual mechanism of action-weak opioid and monoaminergic effects. Tramadol is a racemic mixture and its mechanism of action via opioid and noradrenergic/serotonergic mechanisms is related to the independent effects of its two enantiomers. Interestingly, the enantiomers act synergistically to achieve better antinociceptive effect without enhancing side effects, moreover, lowering respiratory depression and tolerance/dependence. In several post-marketing surveillance studies tramadol is showed as effective as codeine, penthazocine, pethidine and morphine with good tolerability. Tramadol might be analgesic of choice for a wide variety of painful conditions.