We determined the incidence of acute, major complications in a population of 28,395 patients who underwent lumbar laminectomy for discogenic radiculopathy in the United States in 1980. This population was drawn from a broad cross-section of community hospitals and represented 31% of all patients who underwent laminectomy that year for this condition. Our cohort excluded patients with a) operations exceeding two disc levels, b) fusion, c) previous lumbar laminectomy, or d) coexistent discitis, spondylosis, spinal stenosis, myelopathy, or arachnoiditis. The incidence of death was 5.9 per 10,000. The causes of death were septicemia, myocardial infarction, and pulmonary emobolus. The incidence of at least one major complication was 157 per 10,000. The incidences of specific complications were as follows: infection requiring intravenously administered antibiotics, 30.7; major neurological deficit, 29.8; pulmonary embolus, 10.7; and myocardial infarction, 5.6. We studied four additional categories of complication. Patients were counted only when a second operation was required to treat the complication. The categories and incidence per 10,000 were as follows: incisional hematoma, 8.7; cerebrospinal fluid fistula, 10.5; ventral perforation, 1.6; and retention of a foreign body, 0.7. Among the patients whose hospitalizations were otherwise normal, 6.7% received a blood transfusion; of the patients whose hospitalizations were complicated, 24% required transfusion. The demographic characteristics of transfusion. The demographic characteristics of patients with a normal hospitalization were tabulated separately from those whose hospitalizations were complicated. Neurosurgeons performed 60% of the operations, and orthopedic surgeons performed 40%. The speciality of the surgeon was not a factor in determining the risk involved in surgery. Spinal anesthesia was used in 7% of the cases, and no pattern of complications emerged that was uniquely related to that technique.