Aims: Assessment of results in lumbar spine surgery with the SF-36 and NASS (lumbar element) Study design: Prospective monocentric study. Included were all patients with complete data sets. Excluded were patients with incomplete data, who could not read, did not understand german language. Patients and methods: 85 patients were included, 43 women, 42 men. Average age 59 years, SD ±17 years. The patients had surgical treatment (decompression and stabilization) after at least 6 months conservative treatement without amelioration. The questionaires were þlled out the day before operation, after 3, 6 and 12 months. The calculations for the dimensions were the effect size and standardized response mean (delta/SD of delta). Results: ES were large (> 0.8) for all the follow ups (0–3, 0–6, 0–12 months) in the NASS pain and disability dimensions and in the bodily pain and physical function (SF-36) also. ES were small (> 0.2) for all the follow ups (0–3, 0–6, 0–12 months) in the NASS neurology dimension and in the role physical (0–6, 0–12 months) and vitality (0–12 months) (SF-36). SRM showed analogue results. The back pain questions (NASS) depicted greater effects than the leg pain questions. The ES for disturbance was always greater (30%) than that for the frequency. Conclusion: The effect sizes depict large effects regarding back pain, leg pain and disability, small effects regarding neurology. The effects after three/six months are larger than after a year.