Aims. To identify the predictors of changes in alcohol intake among French men. Design. Longitudinal study over a 2-year period. Setting. The GAZEL volunteer cohort comprising workers employed by Electricite de France-Gaz de France. Participants. The study included 11 613 men aged 40-50 years who had answered a self-administered questionnaire in 1989 and 1991. Measurements. Subjects were defined according to initial levels of alcohol intake and changes in that intake (cessation, decrease and increase) and compared with subjects with corresponding levels but unchanged intake by logistic regression. The effects of individual characteristics and of occupational and health conditions were investigated. Findings. Different variables measured in 1989 were predictive of changes in alcohol consumption in 1991, depending on the change. Self-perception of bad health, consumption of sleeping pills and unmarried status were predictive of the cessation of alcohol consumption. Working under favourable conditions (with no specific occupational risks) and being a non-smoker tended to be associated with reduced consumption. Increased consumption was associated with the number of reported disease and the smoking status. Among abstainers or light daily drinkers, being exposed to more than one constraint enlarged the risk of increased consumption. For moderate drinkers, the risk of increased consumption was higher, irrespective of the number of physical constraints. Conclusions. These results highlight the fact that many inter-related factors help to determine changes in drinking habits.