This review summarizes the evidence of stereotactic body radiotherapy (SBRT) as an alternative to surgery (lobectomy and sublobar resection) for stage I NSCLC. Three randomized trials comparing SBRT and surgery were initiated but all three were stopped early due to poor accrual. As the next level of evidence, results from matched-pair analyses performed in single-institutional (n = 4), multi-institutional (n = 3) and population-based (n = 3) settings are available. There was close agreement between all studies that SBRT is at least equivalent to sublobar resection making it the preferred treatment for a high-risk population. SBRT was equivalent to lobectomy in the endpoints of loco-regional control and cancer-specific survival. Disease-free survival and overall survival were inferior after SBRT compared with lobectomy in one and two studies, respectively, and not significantly different in all other studies. Consequently, for patients without relevant comorbidities, who are accepting the risk of a surgical procedure, lobectomy remains the standard of care.