Preoperative and postoperative pulmonary function and body temperature were measured prospectively in 15 patients undergoing either microlumbar discectomy or standard lumbar laminectomy and discectomy for herniated nucleus pulposus. In these otherwise comparable groups patients undergoing standard lumbar laminectomy and discectomy had significant depression in pulmonary function in the first 20 hours postsurgery and febrile temperatures for as long as 48 hours postsurgery. No alteration in pulmonary function or body temperature was observed in those operated on by the microlumbar discectomy technique. We conclude that patients undergoing microlumbar discectomy for lumbar disc herniation have less postsurgical pulmonary morbidity and temperature elevation than those treated by lumbar laminectomy and discectomy.