Epidural opioids are widely used in the management of post- operative pain. On the basis of an extensive review of the literature the authors here present their own interpretation of current knowledge of how the distribution and effectiveness of epidurally administered opiods are fundamentally determined. They conclude that all opioids that are currently being used to treat postoperative epidural pain carry the potential risk of severe side effects if the dose regimens are not tailored to the patients individual analgesic need. This book will serve to stimulate new ideas among pain specialistst.