One strong risk factor of coronary artery disease (CAD), which affects the levels of vitamin C in the blood is cigarette smoking. The supplementary effects of coronary artery bypass grafting (CABG) is smoking cessation by patients. Therefore, the aim of this study was to examine the level of vitamin C in the blood plasma one day before and one month after CABG. Human blood were collected from 20 patients (men); 1 day before and 1 month after CABG. All patients were smoker and after CABG they declared their not smoking. The concentration of vitamin C in the blood plasma was assayed by FIA method with spectrophotometric detection. The mean value of the vitamin C concentration 1 day before CABG was 12.36 +/- 2.84 mu mol/L (mean +/- SD), 1 month after CABG 40.07 +/- 10.95 mu mol/L (mean +/- SD). The average increase in the concentration of vitamin C was 3.27 +/- 0.73 times (mean +/- SD) and showed significant positive correlations (Pearson r = 0.657, p = 0.002). It should be consider incorporating the recommendations of preoperative smoking cessation for at least one month prior to CABG and/or additional supplementation. In addition it would be relevant to monitor the level of vitamin C in the patients' blood in the preoperative period. (C) 2016 Elsevier Masson SAS. All rights reserved.