Background Lumbar disk herniation (LDH) typically causes leg pain and neurologic deficits, but can also be a source of low back pain (LBP). Lumbar microdiskectomy (LMD) is among the most common neurosurgical procedures to relieve radicular symptoms. It is important for both surgeon and patient to understand potential predictors of outcome after LMD. The aim of this study was to investigate if the presence and intensity of preoperative LBP, the ODI score, and analgesic intake can predict the outcome of patients undergoing LMD. Methods This is a single-center retrospective study based on the analysis of prospectively acquired data of patients in the SwissDisc Registry. A total of 685 surgeries on 640 patients who underwent standardized LMD at our institution to treat LDH were included in this study. We performed multivariable linear regression analysis to determine preoperative predictors for patient outcomes based on the Oswestry Disability Index (ODI) scores, recorded on average 39.77 (±33.77) days after surgery. Results Our study confirmed that surgery overall improves patient degree of disability as measured by ODI score. Following model selection using Aikake Information Criterion (AIC), we observed that higher preoperative ODI scores (β: 0.020 [95% CI: 0.008 to 0.031]) and higher number of analgesic medication usage by patients prior to surgery (β: 0.236 [95% CI: 0.057 to 0.415]) were both associated with an increased postoperative ODI score. Conclusion LDH surgery generally improves patient degree of disability. The analysis of patients with a high preoperative ODI score and increased intake of analgesics before surgery predicted a worsening of patients' disability after LMD in this subgroup.