While morphine is historically the gold standard for the management of severe cancer pain, some patients either do not achieve adequate analgesia, or suffer intolerable side effects from this drug. For these patients, alternatives such as hydromorphone are recommended. This review explores the evidence for the efficacy of hydromorphone in the management of pain. A systematic search, from 1966 to 2000, of published and unpublished randomized trials that involved the administration of hydromorphone for both acute and chronic pain conditions in adults and children, was conducted. Forty-three studies were included in the review; 11 involved chronic cancer pain and 32 acute pain. Approximately half the studies received a low quality score. In addition, the heterogeneity of the studies precluded combination of data and results. Overall, hydromorphone appears to be a potent analgesic. The limited number of studies available suggests that there is little difference between hydromorphone and other opioids in terms of analgesic efficacy, adverse effect profile and patient preference. However, most studies involved small numbers of patients and wide ranges in equianalgesic dose ratios, making it difficult to determine real differences between interventions.