Background: Semicarbazide-sensitive amine oxidase (SSAO)/vascular adhesion protein-1 (VAP-1) is involved in the pathogenesis of both atherosclerosis and cancer. Because chemical components and metabolites of cigarettes are deaminated by SSAO, the relationship between smoking and serum SSAO/VAP-1 was studied in humans.Methods: A total of 451 non-diabetic and normoalbuminuric Han Chinese subjects were recruited to participate in this study. Smoking history was obtained by using a questionnaire and those who smoked more than 100 cigarettes during a 6-month period were considered smokers. Serum VAP-1 concentration was measured by time-resolved immunofluorometric assay. Age, gender, waist circumference and estimated glomerular filtration rate (GFR) were adjusted in different statistical models.Results: Smokers were mainly male (85.7% versus 26.3%) and were more obese than nonsmokers (p<0.05). Subjects with higher serum VAP-1 concentrations were older (p<0.001) and tended to have larger waist circumferences and lower estimated GFR. Serum VAP-1 concentration was higher in smokers than in non-smokers (p<0.05) after adjusting for age, gender, waist circumference, estimated GFR, liver biochemistry and lipid profile.Conclusions: Cigarette smoking is associated with elevated serum VAP-1 concentration. Whether VAP-1 and its SSAO activity link the relationship between cigarette smoking, atherosclerosis and cancer requires further investigation.