Background: Welding fumes exposure caused health disorders, one of them are decreasing the level of physical fi tness. This study aimed to analyze the effect of welding fumes exposure with the level of welder'sphysical fi tness.Methods: This cross-sectional using purposive selected by sampling selection method among welders in the muffl er factory at outskirt of Jakarta in 2012. Several characteristic demography, occupational history,and habits were obtained through interview. Welding fumes exposure obtained by semi quantitative method. Physical fi tness was obtained by physical examination using Queen's College Step Test.Results: The total of subjects in this study were 110 people, 19-55 years of age, total duration of work between 1-16 years. We found that there were no signifi cant association between the age and physical activity of respondents with the level of welder physical fi tness. We noted negative correlation between the total fume exposure, body mass index, duration of smoking habits and the level of welder physical fi tness. The correlation were: the total fume exposure [regression coeffi cient (r)= -0,07; 95% confi dence interval (CI)= -0,10;-0,04]; body mass index (r= -0,38; 95% CI= -0,64;-0,09); and duration of smoking habits (r= -0,16; 95% CI= -0,28;-0,04).Conclusion: Increase in total welding fumes exposure, body mass index, and duration of smoking habit will be decrease welder physical fi tness. (Health Science Indones 2012;1:37-40)