Purpose: R0 resection with a wide surgical margin is the gold standard for hepatocellular carcinoma (HCC), yet R0 resection with narrow margins and even R1 resection is not uncommon in real-world clinical practice. We sought to use a propensity-matched analysis to characterize the efficacy of adjuvant radiation therapy on long-term oncological survival after hepatectomy for HCC with narrow or positive margins. Methods and Materials: Using a multi-institutional database, patients with HCC who underwent hepatectomy with negative margins of 0.1 to 1.0 cm or pathologically positive margins were analyzed. Using propensity score matching (PSM) and multivariate Cox-regression analysis, the effect of adjuvant radiation therapy on long-term overall survival (OS) and recurrence-free survival (RFS) was evaluated. Results: Among 683 patients who met inclusion criteria, 82 patients received adjuvant radiation therapy within 10 weeks after surgery. Radiation therapy-related major toxic effects were minimal among patients receiving adjuvant radiation therapy. PSM analysis created 78 matched pairs of patients. In the PSM cohort, median OS and RFS among patients treated with adjuvant radiation therapy were more favorable than individuals who were not treated (72.5 and 37.3 months versus 52.5 and 24.0 months, both P <.05). After adjustment for other confounding factors on multivariate analyses, adjuvant radiation therapy remained independently associated with favorable OS and RFS after hepatectomy with close/positive surgical margins for HCC (hazard ratios, 0.821 and 0.827, respectively). Conclusions: Despite the lack of consensus on the role of adjuvant radiation therapy after HCC resection, this PSM analysis suggested improved OS and RFS with adjuvant radiation therapy after hepatectomy with close/positive surgical margins for HCC. Future randomized controlled trials are needed to further define the survival benefit of adjuvant radiation therapy for patients with HCC. (C) 2022 Elsevier Inc. All rights reserved.