BACKGROUND: The aim of this study was to quantify the risk of late recurrence in patients with stage IA non-small cell lung cancer who remained recurrence-free more than 5 years after surgical resection METHODS: A total of 519 patients with stage IA underwent complete resection at our hospital from August 1992 to December 2002. The recurrence-free rate was calculated from a base point of five years after resection of the primary tumor to the time of first recurrence or to the time of final follow-up, and was analyzed using the Kaplan-Meier method. RESULTS: Of 519 patients, 434 remained recurrence-free at 5 years. Of these, 21 cases (4.8%) experienced late recurrence after 5 years. The median recurrence-free interval was 14 months, with a 5-year recurrence-free rate of 93%, calculated at a reference point of 5 years after surgery. The 5-year recurrence-free rate was 84% in those with vascular invasion compared with 95% in patients without vascular invasion (p < 0.001). CONCLUSION: Patients with stage IA non-small cell lung cancer with vascular invasion are at risk of late recurrence more than 5 years after surgery. For patients with stage IA non-small cell lung cancer with vascular invasion, absence of recurrence at 5 years does not mean that the lung cancer is cured. In contrast, patients without vascular invasion can be considered cured if they remain recurrence-free 5 years after resection.