Research on archival samples and population-based studies have shown that light-eyed individuals, and especially blue-eyed individuals, consumed more alcohol than dark-eyed individuals. In this field study carried out in a French barroom, we hypothesized that the average blood alcohol concentration of participants with blue eyes would be higher than people with other eye color. We measured blood alcohol concentration with a breathanalyzer among 61 customers from various occupational backgrounds, and calculated the association between eye color and BAC. Results showed that among males and females, irrespective of age, participants with blue eyes had a higher BAC than the others. The mean BAC was also higher among men than women. This ecological result suggests that iris pigmentation represents a biological marker for underlying factors involved in higher alcohol consumption. Various hypothetical mechanisms are considered.