Epidemiological studies of the relationships between pulmonary function and reported alcohol intake showed inconsistent results. The use of biological markers of alcohol is needed. The objective of this study was to assess the relationships of alcohol consumption, assessed by a standardized questionnaire, and gamma-glutamyl transpeptidase (GGT), to forced expiratory volume in 1 sec (FEV1) level and decline over 10 years, in working men. Three hundred twenty-eight policemen aged 22-55 years were examined in 1980 (first survey) and again in 1990 (second survey). The two cross-sectional analyses used the 1980 data and the 1990 data separately. Longitudinal analysis used 1980 alcohol consumption and GGT values, and 10-year FEV1 decline. In both cross-sectional surveys, elevated alcohol consumption was significantly associated with impaired age-adjusted and height-adjusted FEV1. Further adjustment for smoking habit, education level, and asthmatic status did not alter these results. An increase of 25 g/day of alcohol was associated with 50.0 ml (95% confidence interval: 1.5 to 98.5) and 55.3 ml (95% confidence interval: 7.8 to 102.8) decrease of corresponding multivariate-adjusted FEV1 in 1980 and in 1990, respectively. GGT was also negatively associated with FEV1 in both cross-sectional surveys. Similar patterns of associations were also observed between vital capacity measurements and alcohol variables. In the longitudinal analysis, there was no relationship between either alcohol consumption or GGT and FEV1 decline. Findings suggest that alcohol consumption was associated with impaired lung function, but there was no evidence of accelerated FEV1 decline over 10 years related to alcohol consumption in this "healthy" population of middle-aged men.