Although standard surgical treatment of stage I non-small cell lung cancer (NSCLC) is lobectomy, sublobar resection may be elected for small-sized (≤2 cm) peripheral tumors. Our aim was examine the need for completion lobectomy in the event of confirmed pleural or lymphovascular invasion after sublobar resection of NSCLC. A total of 271 consecutive patients undergoing curative resection of stage I NSCLC ≤2 cm were reviewed retrospectively, analyzing clinicopathologic findings and survival times of those with invasion-positive (visceral pleural or lymphovascular invasion) or invasion-negative (neither visceral pleural nor lymphovascular invasion) tumors by surgical approach (sublobar resection vs lobectomy). Aside from age and pulmonary function, clinicopathologic characteristics of the patient subsets did not differ significantly, nor did 5-year recurrence-free survival rates of surgical subsets (sublobar resection vs lobectomy) in respective tumor groups (invasion-positive 78.9 vs 79.8%, p = 0.928; invasion-negative 80.2 vs 85.4%, p = 0.505). In multivariate analysis, dissected lymph node count was the sole parameter significantly impacting recurrence of stage I invasion-positive NSCLC (hazard ratio = 0.914, 95% confidence interval 0.845-0.988; p = 0.023). Sublobar resection was not a risk factor for recurrence. Survival rates for patients with small-sized (≤2 cm) NSCLC and visceral pleural or lymphovascular invasion did not differ significantly, whether sublobar resection or lobectomy was done. Hence, completion lobectomy is unnecessary in this setting.