Epidural morphine injection was done in nineteen patients who had been admitted from March to August 1990 to the Intensive Care Unit, Severance Hospital, Yonsei Medical Center for respiratory care including ventilator care. Morphine suplphate, 2.67 ± 0.27 mg was injected one to three times to four patients after chest trauma, and to fifteen patients after thoracotomy. Tidal volume and vital capacity were increased from 4.45 ± 0.48 and 8.31 ± 0.50 to 6.91 ± 0.41 and 12.81 ± 0.73 mg/kg. However, respiratory rates decreased from 26.07 ± 1.41 to 20.07 ± 1.16/min. Inspiratory force increased from -13.40 ± 1.31 to -26.53 ± 1.82 cmH₂O. Pain score decreased from 9.22 ± 0.57 to 3.56 ± 0.83 during this period. P_aCO₂ did not differ significantly (39.33 ± 1.13 and 39.48 ± 1.42 mmHg). Side effects such as pruritis and urinary retention were treated with naloxone 7 approximately 10 ng/kg/min. Mean arterial pressure and pulse rates stayed stable during the study periods. Ventilator hours and ICU stays differed from the control group. However, the duration was not statistically significant. The control group consisted of patients who were admitted during the six months from September 1989 to February 1990 to the ICU for respiratory care, without epidural morphine injection.