BACKGROUND CONTEXT: The proportion of patients who undergo lumbar microdiscectomy due to lumbar radiculopathy who are also overweight or obese is high. However, whether high body mass index (BMI) affects clinical outcomes is not well-studied. PURPOSE: To investigate the difference in the clinical course between normal weight, overweight, and obese patients with radiculopathy who underwent lumbar microdiscectomy followed by physical therapy and to evaluate whether high BMI is associated with poor recovery. STUDY DESIGN/SETTING: A prospective cohort study with a 12-month follow-up was conducted in a multidisciplinary clinic. PATIENT SAMPLE: We included 583 patients (median (IQR) age: 45 (35-52) years; 41.0% female) with clinical signs and symptoms of lumbar radiculopathy, consistent with magnetic resonance imaging findings, who underwent microdiscectomy followed by post-operative physical therapy. OUTCOME MEASURES: Outcomes were leg pain and back pain intensity measured with a visual analogue scale, disability measured with the Roland Morris Disability Questionnaire at 3 and 12-month follow-ups, and complications. METHODS: Patients were classified as being normal weight (46.9%), overweight (38.4%), or obese (14.7%). A linear mixed-effects model was used to assess the difference in the clinical course of pain and disability between the three BMI categories. The association between BMI and outcomes was evaluated using univariable and multivariable logistic regression analyses. RESULTS: All three patient groups experienced a significant improvement in leg pain, back pain, and disability over 3 and 12-month follow-up. Patients who were overweight, obese, or normal weight experienced comparable leg pain (p=0.14) and disability (p=0.06) over the clinical course (p=0.14); however, obese patients experienced higher back pain (MD = -6.81 [95%CI: -13.50 - -0.14]; p=0.03). The difference in back pain scores was not clinically relevant. CONCLUSION: In the first year following lumbar microdiscectomy, patients demonstrated clinical improvements and complications that were unrelated to their preoperative BMI.