The authors investigated endothelial function using flow-mediated dilatation (FMD) in burn patients. This study was done in burn patients with specific criteria on admission. Blood lipid profile at 1st day, high-sensitivity C-reactive protein, and FMD were assessed at 1st and 7th days, as well as at 1st and 3rd months. The highest values of high-sensitivity C-reactive protein were detected on the 7th day, which were significantly higher than those at 1st and 3rd months. The lowest value of FMD was observed on the 7th day. FMD values were higher during the 1st month compared with the 7th day. The highest value of FMD was detected in the 3rd month. It was found that FMD values measured at 7th day and 1st month were significantly lower in patients with a burn percentage of 40 or greater. Our results suggest that inflammation is more prominent on 7th day following burn. The decrease in FMD values on 7th day after injury can be attributed to endothelial damage. The increase in FMD on 3rd month after burn is attributable to effective burn treatment and gradual decrease of inflammatory mediators. The data from this study suggest that there is endothelial dysfunction and low-grade inflammation in burn patients. This condition is more prominent in patients with a burn ratio greater than 40%. Burn patients more frequently have impaired FMD, which may be indicative of arterial endothelial dysfunction and a marker for increased atherosclerosis.