From a survey of the recent literature on chronic intraspinal morphine administration for cancer pain concerning 412 cases, the present authors observe that: 1. data regarding follow-up on pain relief and complications are lacking; 2. continuous administration by closed systems shows more efficacy in long-term pain relief; 3. tolerance, although not reported by all authors, is present and becomes remarkable in prolonged administration; 4. serious side-effects are less frequent with the epidural administration technique. These data are confirmed by the present authors' clinical experience of 22 patients treated with epidural morphine administration and 53 patients treated with intrathecal morphine. The widespread use of these methods is limited not only by technical complications but also by the existence of certain types of pain which do not respond to morphine and which may develop, as part of the evolution of the neoplastic disease, even during treatment with intraspinal morphine.