Lung cancer is the leading cause of cancer-related mortality and responsible for 1.6 million deaths per year through world-wide. Surgical resection with negative margin combined with the adjuvant therapy [except for stage IA and IB (<4 cm)] is the Standard treatment for early-stage Non-small cell lung cancer (NSCLC). Early-stage NSCLC, however, has relapse rate over 40% mostly at distant sites. Therefore, high relapse rate necessitates urgent novel biomarker for these patients. In this study, we aim to evaluate the predictive and prognostic role of FOXP3+ Treg cells along with well defined Clinicohistopathological factors in early-stage non-small cell lung cancer (NSCLC). FOXP3 expression in tumor infiltrating lymphocytes (TIL) was examined by immunohistochemical staining from resected early-stage 48 NSCLC patients. Data of patients and FOXP3 expression status along with common clinicohistopathological prognostic factors were evaluated retrospectively. Median age of patients was 62 years-old (range 43–78). Mean follow-up, median overall survival (OS), and disease-free survival (DFS) were 49, 49 and 30 months, respectively. FOXP3 expression was positive in 23 (47.9%) patients. Adjuvant chemotherapy (4 cycles of cisplatin-vinorelbine) was given to 16 patients (33.3%) at physician discretion. Patients with a FOXP3 expression of 25% or higher significantly lower OS and DFS when compared with patients with a FOXP3 staining lower than 25% with p-value of 0.016 and 0.032, respectively. In the patients with high FOXP3 expression, platin-based adjuvant chemotherapy had showed a detrimental effect on DFS and OS. These results suggest that FOXP3 expression may be used as useful prognostic biomarker in resected NSCLC. Our findings also suggest that resected NSCLC patients with FOXP3 expression of 25% or higher staining intensity may not get any benefit even disfavor from adjuvant platin chemotherapy.