OBJECTIVE The purpose of this study was to investigate whether the intraoperative application of an epidural steroid (ES) on the decompressed nerve root improves short- and midterm subjective and objective clinical outcomes after lumbar microdiscectomy. METHODS This study was a retrospective analysis of a 2-center database including consecutive cases in which patients underwent lumbar microdiscectomy. All patients who received ES application (40 mg triamcinolone, ES group) were matched by age and sex to patients who had not received ES application (control group). Objective functional impairment (OFI) was determined using age- and sex-adjusted T-scores of the Timed Up and Go (TUG) test. Back and leg pain (visual analog scale), functional impairment (Oswestry Disability Index [ODI], Roland-Morris Disability Index [RMDI], and health-related quality of life (hrQoL; 12-Item Short Form Health Survey [SF-12] physical component summary [PSC] score and EuroQol [EQ-5D index]) were measured at baseline, on postoperative day 3, and at postoperative week 6. RESULTS Fifty-three patients who received ES application were matched with 101 controls. There were no baseline demographic or disease-specific differences between the study groups, and preoperative pain, functional impairment, and hrQoL were similar. On postoperative day 3, the ES group had less disability on the RMDI (mean 7.4 vs 10.3, p = 0.003) and higher hrQoL as determined by the SF-12 PCS (36.5 vs 32.7, p = 0.004). At week 6, the ES group had less disability on the RMDI (3.6 vs 5.7, p = 0.050) and on the ODI by trend (17.0 vs 24.4, p = 0.056); better hrQoL, determined by the SF-12 PCS (44.3 vs 39.9, p = 0.018); and lower OFI (TUG test T-score 100.5 vs 110.2, p = 0.005). The week 6 responder status based on the minimum clinically important difference (MCID) was similar in the ES and control groups for each metric. The rates and severity of complications were similar, with a 3.8% and 4.0% reoperation rate in the ES group and control group, respectively (p = 0.272). There was a tendency for shorter hospitalization in the ES group (5.0 vs 5.8 days, p = 0.066). CONCLUSIONS Intraoperative ES application on the decompressed nerve root is an effective adjunct treatment that may lower subjective and objective functional impairment and increase hrQoL in the short and intermediate term after lumbar microdiscectomy. However, group differences were lower than the commonly accepted MCIDs for each metric, indicating that the effect size of the benefit is limited. ■ CLASSIFICATION OF EVIDENCE Type of question: therapeutic; study design: retrospective cohort trial; evidence: Class II.