PURPOSE: To retrospectively evaluate long-term survival outcomes of radiofrequency (RF) ablation of colorectal lung metastases and evaluate factors associated with improved survival. MATERIALS AND METHODS: Eighty-four patients (46 male and 38 female; median age, 65 y) with 172 colorectal lung metastases (median size, 1.2 cm) underwent 113 RF ablation sessions. Thirteen patients had viable extrapulmonary recurrences at the time of RF ablation. The primary endpoint was patient survival. Prognostic factors associated with survival were determined by univariate and multivariate analyses. Secondary endpoints were local tumor progression and adverse events (per National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0). RESULTS: During follow-up (median duration, 37.5 mo), 36 patients (42.9%) died. The estimated overall survival (OS) rates were 95.2%, 65.0%, and 51.6% at 1, 3, and 5 years, respectively (median OS time, 67.0 mo). Multivariate analysis revealed that a carcinoembryonic antigen (CEA) level of at least 5 ng/mL before RF ablation (P = .03) and the presence of viable extrapulmonary recurrences at the time of RF ablation (P = .001) were independent negative prognostic factors. The local tumor progression rate was 14.0% (24 of 172 tumors). Grade 3 adverse events were observed after two sessions (1.8%), and grade 4/5 adverse events were not observed. CONCLUSIONS: RF ablation of colorectal lung metastases provided favorable long-term survival with a low incidence of severe adverse events. Independent prognostic factors were a high CEA level before RF ablation and the presence of viable extrapulmonary recurrences at the time of RF ablation.