PURPOSE: To retrospectively evaluate the midterm outcomes (eg, safety, local efficacy, and survival) after radiofrequency (RF) ablation for pulmonary metastases from colorectal cancer. MATERIALS AND METHODS: Twenty-seven patients (19 men and eight women; mean age, 61.6 years) with 49 pulmonary metastases (mean long axis diameter, 1.5 cm) from colorectal cancer underwent 41 percutaneous computed tomography (CT)-guided RF ablation sessions. Follow-up examinations were performed with CT by using contrast medium administration in all patients; positron emission tomography was performed in five patients. The safety of the procedure, local tumor control, and patient survival were evaluated. Multiple variables were analyzed to determine prognostic factors. RESULTS: Pneumothorax occurred after 20 of the 41 sessions (49%), three of which necessitated chest tube placement. A small pleural effusion was found after six of the 41 sessions (15%). No major hemorrhagic event was observed. None of the patients died due to the procedure. The median follow-up period was 20.1 months (range, 11.2-47.7 months). The primary and secondary technique effectiveness rates were 72% and 85%, respectively, at 1 year, 56% and 62% at 2 years, and 56% and 62% at 3 years. The overall survival rates after RF ablation were 96% at 1 year, 54% at 2 years, and 48% at 3 years. The presence of extrapulmonary metastasis was determined to be a prognostic factor (P = .001). CONCLUSIONS: The midterm outcomes of percutaneous RF ablation for colorectal pulmonary metastases appear promising. The presence of extrapulmonary metastasis had an adverse effect on survival after RF ablation.