Stage I non-small cell lung cancer (NSCLC) show a highly variable biological behavior which cannot be accurately predicted by the current available prognostic markers. Platelet plays a significant role in cancer cell growth, progression and metastasis. This study aimed to investigate whether preoperative platelet count correlate with clinical prognosis in localized NSCLC. A retrospective clinical analysis was designed for a total of 234 stage I NSCLC patients in our hospital between October 2006 and December 2009. Pre-operative platelet count was measured. The association of platelet count with clinical pathological factors and patient outcome was evaluated. A significant correlation was detected between platelet count and tumor cell differentiation and T stage. Patients with elevated platelet count had an elevated risk of disease progression and death compared to patients with normal platelet count. The hazard ratio was 5.314 (95% confidence interval [CI] 2.750-10.269) for disease progression and 3.139 (95% CI 1.227-8.034) for death. The trend linking increasing platelet count with risk was also statistically significant for both the outcomes (p < 0.05). These finding demonstrate that preoperative platelet count is a useful predictor of high risk progression and poor prognosis in stage I NSCLC patients.