is the most common mutation in primary lung adenocarcinoma. Phase I clinical trials have demonstrated encouraging clinical activity of inhibitors in the metastatic setting. We investigated disease-free survival (DFS) and tumor genomic features in patients with surgically resected -mutant lung adenocarcinoma. Patients who underwent resection of stage I-III lung adenocarcinoma and next-generation sequencing (NGS) were evaluated. Exclusion criteria were receipt of induction therapy, incomplete resection, and low-quality NGS. Mutations were classified as wild-type ( ), G12C ( ), or non-G12C ( ). DFS was compared between groups using the log-rank test; factors associated with DFS were assessed using Cox regression. Mutual exclusivity and cooccurrence, tumor clonality, and mutational signatures were assessed. In total, 604 patients were included: 374 (62%), 95 (16%), and 135 (22%). Three-year DFS was not different between -mutant and tumors. However, 3-year DFS was worse in patients with than tumors (log-rank = 0.029). tumors had more lymphovascular invasion (51% vs. 37%; = 0.032) and higher tumor mutation burden median (interquartile range), 7.0 (5.3-10.8) vs. 6.1 (3.5-9.7); = 0.021, compared with tumors. mutation was independently associated with worse DFS on multivariable analysis. Our DFS findings were externally validated in an independent The Cancer Genome Atlas cohort. mutations are associated with worse DFS after complete resection of stage I-III lung adenocarcinoma. These tumors harbor more aggressive clinicopathologic and genomic features than other -mutant tumors. We identified a high-risk group for whom inhibitors may be investigated to improve survival.