Background The identification of psychological risk factors is important for the selection of patients before spinal surgery. Moreover, the effect of surgical decompression in lumbar spinal stenosis (LSS) on psychological outcome is not previously well analyzed. Aim of paper to investigate clinical and psychological outcome after surgery for LSS and the effect of depressive symptoms and anxiety on the clinical outcome. Materials and methods A total of 25 patients with symptomatic LSS underwent decompressive surgery with or without spinal stabilization were prospectively enrolled in this observational surgery. The Symptom Checklist-90-Revised (SCL-90-R) was used to assess global psychological distress with a summary score termed Global Severity Index (GSI) and single psychological disorders including depression (DEP) and anxiety (ANX). The clinical outcome of surgery was evaluated with the Oswestry Disability Index (ODI) and visual analogue scale (VAS) pain assessment. Results Compared with baseline, there was a statistically significant improvement in VAS, ODI and GSI after surgery (p<0.05) in all patients. Univariate analysis revealed that patients with high GSI and anxiety and depression scores had significantly higher ODI and VAS scores in the follow-up with a bad outcome. Conclusions Surgery for spinal stenosis was effective to treat pain and disability. In this prospective study baseline global psychological distress, depression and anxiety were associated with poorer clinical outcome.