Pain is protective mechanism for the body, it occurs whenever any tissue is being damaged or traumatized as in surgical trauma. The use of epidural and intraspinal narcotics for the relief of postoperative pain has been due to the discovery of opiate receptors and their locations along the pain pathway and other areas of the C.N.S. The pharmacokinetic parameters especially lipid solubility, ionization and molecular weight seem to be responsible for the pharmacodynamic variations (e.g. analgesic efficacy, onset, duration and side effects) between the opioid narcotics. This study was carried out on 80 patients divided into 4 groups (20 in each group) undergoing orthopedic surgery and receiving postoperative analgesia with I.M. morphine, epidural morphine in saline, epidural morphine with adrenaline and epidural morphine in dextran 70 respectively . The patients were assessed and monitored clinically regarding pain score, respiratory rate, blood pressure and heart rate. Serum morphine levels were determined using I125 radioimmunoassay. This study proved that, I.M. and epidural morphine administration provides effective pain relief in orthopedic surgery. Analgesia after epidural morphine is of slow onset and longer duration. There is no relationship between serum morphine levels and quality of analgesia. Addition of adrenaline or dextran 70 may prolong its analgesic duration. The respiratory and cardiovascular changes are insignificant. Side effects occur more with epidural morphine especially with addition of adrenaline in the form of respiratory depression, pruritus, nausea and vomiting and urinary retention.