After abdominal surgery, it is well known that a significant decrease in ventilatory function, arterial oxygenation, and coughing ability occurs and this may lead to retainment of bronchial secretions and eventually atelectasie. The author selected 32 patients who received abdominal surgery under general anesthesia. A small dose of morphine was administered intrathecally before induction of general anesthesia, in an attempt to relive postoperative pain. The development of pain was observed until it was sufficient enough to require intramusclar or intravenous injections of analgesics. The results of this study were as follows: 1) A small dose of intrathecally injected morphine did not affect postoperative arterial blood pressure and respiratory rate of the patients. 2) Fifty percent of the patients required no analgesics for pain control within 24 hours of postoperative periods. Intrathecal dose of morphine from 0.1 to 0.3 mg had the similar effect for the postoperative pain control. 3) Central nevous system depression was not noted, but side effects such as nausa(44%) and pruritus(19%) were commonly observed.