Fish consumption is the major dietary source of EPA and DHA, which according to rodent experiments may reduce body fat mass and prevent obesity. However, human studies have suggested that fish consumption has no appreciable association with body-weight gain. We investigated the associations between fish consumption and subsequent change in waist circumference. Sex, age and waist circumference at enrolment were considered as potential effect modifiers. Women and men (n 89 432) participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) were followed for a median of 5·5 years. Mixed-effect linear regression was used to investigate the associations between fish consumption and subsequent change in waist circumference. Among all participants, the average annual change in waist circumference was - 0·01 cm/10 g higher total fish consumption per d (95 % CI - 0·01, 0·00) and - 0·01 cm/10 g higher fatty fish consumption per d (95 % CI - 0·02, - 0·01), after adjustment for potential confounders. Lean fish consumption was not associated with change in waist circumference. Adjustment for potential over- or underestimation of fish consumption measurements did not systematically change the observed associations, but the 95 % CI became slightly wider. The results in subgroups from analyses stratified by sex, age or waist circumference at enrolment were not systematically different. In conclusion, the present study suggests that fish consumption does not prevent increase in waist circumference.