The object of this review is to summarize the current knowledge of morphine and morphinelike drugs. If used wisely, morphine, the oldest agent, is still one of the best. Starting in 1898 with heroin, an increasing number of morphinelike drugs have been created with the hope of improving on morphine. The array of compounds now available is made more labyrinthine by the doubtful virtuosity of trademark inventors. Whether any of the newer compounds, including meperidine, have any significant advantage over morphine or whether it is possible to separate the desired effects of these potent agents from the undesirable effects is questionable. A practical classification depends on the degree of analgesia and the duration of action. These agents can now be used more safely because of the development of such potent antagonists as nalorphine and levallorphan.