Background: The influence of surgical margin status on long-term outcomes of patients undergoing adrenal resection for ACC remains not well defined. We studied the impact of surgical tumor margin status on recurrence-free survival (RFS) and overall survival (OS) of patients undergoing resection for ACC. Methods: A total of 165 patients who underwent adrenal resection for ACC and met inclusion criteria were identified form a multi-institutional database. Clinicopathological data, pathologic margin status, and long-term outcomes were assessed. Patients were stratified into two groups based on margin status: R0 (margin >1 mm) versus R1. Results: R0 resection was achieved in 126 patients (76.4 %), whereas 39 patients (23.6 %) had an R1 resection. Median and 5-year OS for patients undergoing R0 resection were 96.3 months and 64.8 % versus 25.1 months and 33.8 % for patients undergoing an R1 resection (both p < 0.001). On multivariable analysis, surgical margin status was an independent predictor of worse OS (hazard ratio [HR] 2.22, 95 % confidence interval [CI] 1.03–4.77; p = 0.04). The incidence of recurrence also differed between the two groups; 5-year RFS was 30.3 % among patients with an R0 resection versus 13.8 % among patients who had an R1 resection (p = 0.03). Lymph node metastasis (N1) was an independent predictor of RFS (HR 2.70, 95 % CI 1.04–6.99; p = 0.04). Conclusions: A positive margin after ACC resection was associated with worse long-term survival. Patient selection and an emphasis on surgical technique to achieve R0 margins are pivotal to optimizing the best chance for long-term outcome among patients with ACC.