Objective: To evaluate the effect of chronic biomass fuel (BMF) smoke exposure on peripheral endothelial functions. Methods: Forty-seven healthy subjects who have been exposed to BMF smoke since birth (mean age 31.6±6.8 years, 21 male) were enrolled in the present cross-sectional observational study. The control group consisted of 32 healthy subjects (mean age 27.9±4.4 years, 11 male). The carotid intima media thickness (CIMT), flow associated dilatation (FAD %) and endothelium independent vasodilatation (GTN %) were assessed in all subjects. The carotid CIMT was defined as the distance between the leading edge of the lumen–intima and the media–adventitia interfaces. FAD % was defined as the percentage change in the internal diameter of the brachial artery during reactive hyperemia related to the baseline. GTN % was defined as the change in diameter in response to the application of 400 µg of glyceril trinitrate relative to the baseline scan at the end of the fourth minute. Statistical analysis was performed using Student’s t-test, Chi-square test and Spearman rank order correlation analysis. Results: The average exposure time of the subjects to biomass fuel smoke was 31.7±6.6 years. They have been exposed to dung inhalation products meanly 8.3±1.8 months in a year seasonally. The average daily exposure time was 15.7±3.3 hours. CIMT values of the two groups were not statistically different from each other (0.47±0.09 vs. 0.49±0.06 mm, p=0.138). However, a markedly reduced FAD % was determined in the study group (5.06±4.95 vs. 10.7±4.64, p<0.001). And GTN % of the BMF exposed group was significantly lower than the control group (14.41±8.47 vs. 21.85±7.87, p<0.001). Conclusion: FAD % and GTN % are markedly reduced in the individuals who have been exposed to BMF smoke inhalation products. Therefore, chronic BMF smoke exposure may be a risk factor for the development of endothelial dysfunction.