PURPOSE: Surgical drains are routinely used to prevent the accumulation of fluid at the operative site, an effect known to decrease the risk of seroma and theoretically lower the chance of abscess or small hematoma formation. Despite these potential benefits, significant debate exists in the literature regarding the risk that such drains might be imparting on the development of surgical site infections (SSIs), and the use of prophylactic antibiotics to “cover the drain” remains a common practice despite scant evidence that closed suction drains increase the risk for SSI. The purpose of the present study is to examine our database of over 12 years of muscle flap closure following complex spinal surgery to determine the effect of drain dwell duration on postoperative wound complications including SSI. METHODS: For this retrospective review, 301 consecutive index cases of complex spine surgery with immediate muscle flap closure (paraspinous, trapezius, latissimus dorsi, and/or thoracolumbar fascia) by the senior author from 2006 to 2018 were identified. The electronic medical record was reviewed for patient characteristics, perioperative details, and outcomes. Examination of the effect of median drain dwell duration on the primary endpoint, SSI, was first conducted via the Mann-Whitney test followed by univariable logistic regression analysis for both the primary endpoint and secondary endpoints including wound complication requiring reoperation and the need for hardware removal due to infection. RESULTS: The cohort was 50.8% male and with an average age of 59.0 ± 18.0 years and body mass index of 27.8 ± 6.7 kg/m2. In 85% of cases, ≥1 drain was in intimate contact with the hardware and/or bone graft, and patients received no >24 hours of postoperative intravenous cefazolin (or other appropriate perioperative coverage in case of documented allergy) unless further antibiotics were indicated. There were 15 cases of SSI, overall, making for an incidence of 4.9%. Drain durations were clearly documented in 271 cases. Median drain dwell duration among these cases was 19 days (interquartile range [IQR], 14–27 days), overall, 19 days (IQR, 14–27 days) among cases which did not develop SSI, and 22 days (IQR, 15–30 days) among cases which did develop SSI (P = 0.231). Univariable logistic regression analysis also demonstrated no increased risk with longer drain dwell times for the development of SSI (odds ratio [OR], 1.03; 95% confidence interval [CI], 0.98–1.08; P = 0.282), wound complication requiring reoperation (OR, 1.02; 95% CI, 0.96–1.09; P = 0.559), or subsequent removal of hardware due to infection (OR, 1.03; 95% CI, 0.95–1.11; P = 0.528). CONCLUSIONS: In this large retrospective series of 301 cases spanning over 12 years, we demonstrate that increased drain dwell duration is not associated with SSI, wound complication requiring reoperation, or need for hardware removal due to infection. These findings, particularly in light of the high-risk nature of the cohort in which 85% of patients had drains placed adjacent to hardware and/or bone graft, contribute to the evidence that increased drain dwell times do not place patients at greater risk of SSI and that such patients do not need prophylactic antibiotics for drain coverage.