BACKGROUND: Previous studies have failed to demonstrate statistically significant differences in postsurgical outcomes between operative cases featuring resident participation compared to attending only; however, the effects of level of postgraduate year (PGY) training have not been explored. OBJECTIVE: To correlate different PGYs in neurosurgery with 30-d postoperative outcomes. METHODS: Using National Surgical Quality Improvement Program 2005-2014, adult neurosurgical cases were divided into subspecialties: spine, open-vascular, cranial, and functional in teaching institutions. Comparison groups: cases involving junior residents (PGY 1-PGY 3), mid-level residents (PGY 4 + PGY 5), and senior residents (PGY 6 + PGY 7). Primary outcome measures included anywound disruption (surgical site infections and/or wound dehiscence), Clavien-Dindo grade IV (life-threatening) complications, and death. RESULTS: Compared to junior residents (n = 3729) and mid-level residents (n = 2779), senior residents (n = 3692) operated on patients with a greater comorbidity burden, as reflected by higher American Society of Anesthesiology classifications and decreased level of functional status. Cases with senior resident participation experienced the highest percentages of postoperative wound complications (P = .005), Clavien-Dindo grade IV complications (P=.001), and death (P=.035). However, following multivariable regression, level of residency training in neurosurgery did not predict any of the 3 primary outcome measures. Compared to spinal cases, cranial cases predicted a higher incidence of lifethreatening complications (odds ratio 1.84, P< .001). CONCLUSION: Cases in the senior resident cohort were more technically challenging and exhibited a higher comorbidity burden preoperatively; however, level of neurosurgical training did not predict any wound disruption, life-threatening complications, or death. Residents still provide safe and effective assistance to attending neurosurgeons.