The prevalence of obesity among the population is increasing, including in many elderly people. The purpose of this study was to evaluate whether lumbar spinal surgery in elderly patients with different body mass indices influences pain, satisfaction rate, and activities of daily living. Two hundred ninety-eight elderly patients (older than 65 years), 153 women and 145 men, who had decompressive laminectomy, discectomy, or combinations of these procedures during 1990 to 2000 were followed up. Indications for surgery included limitation in doing activities of daily living, severe pain, or both. The patients were classified into one of four categories in terms of their body mass index. The operative parameters, pain reduction, satisfaction rate, and activities of daily living using the Barthel index were assessed. The more obese patients were younger, tended to be female, and were more symptomatic. All four groups of patients had reduction in pain, improvement in activities of daily living, and were satisfied with the operation. Our data suggest that it is reasonable to operate on patients who are elderly and obese and who have lumbar symptoms, with the appropriate indications.