Abstract: Objective To investigate the relationship between the serum levels of mitochondrial coupling factor-6（CF6）,prostacyclin（PGI2）and nitric oxide（NO）in healthy smokers. Methods Ninety volunteers were enrolled in this study including 59healthy smokers37cases with cigarette index（CI）≤200and 22cases CI＞200and 31 healthy non-smokers（CI=0）.The serum levels of CF6and PGI2 were tested by enzyme-linked immunosorbent assay（ELISA）,while the serum level of NO was determined by nitrate reductase method. Results The serum levels of CF6in CI＞200group（208.85±14.18）ng/Lwere higher than those in CI=0（163.81±14.83）ng/Land CI ≤200group（188.53±9.29）ng/L. The serum concentrations of PGI2in group which CI＞200 （80.61± 6.87）ng/Lwere lower than CI=0 （100.19±4.10）group and CI≤200group （88.94±4.16）ng/L. The serum concentrations of NO tested in CI＞200group （62.74±10.74）was lower than CI=0 （88.67± 9.55）and CI≤200group（75.95±7.29）μmol/L. CF6had a significantly negative correlation with serum levels of PGI2and NO（r=-0.418,r=-0.326,both P＜0.05）. Multivariate analysis showed that CI was independently associated with CF6,PGI2and NO（β=2.331,-0.422,-0.231,all P＜0.05）. Conclusion Smoking can cause an increase in serum level of CF6and a decrease in the serum level of NO and PGI2.