This study correlated the executive frontal functions with blood alcohol concentration (BAC) in night drivers in a Brazilian city. Of 592 drivers randomly recruited between December 17, 2005 and May 5, 2006, during nighttime hours on main streets or avenues with intense vehicle traffic in Vitória, Brazil, 444 had the BAC determined by a portable digital breath alcohol analyzer and 389 were submitted to a frontal function examination by a frontal assessment battery (FAB). A high percentage (24.4%) of drivers presented alcohol in their blood. Most of these drivers were male (82%), and nearly half (43.7%) were young adults (aged between 20 and 30 years). The results showed an inverse relationship between the BAC and FAB total scores, with a higher BAC corresponding to a smaller FAB total score, delineating a progressive decrease in frontal function with increasing concentrations of alcohol. The most intriguing result was that alcohol-induced impairment on frontal executive function was particularly important in young adults, and more specifically in the motor programming subset of FAB, an executive function highly involved in driving skills. Considering the worldwide evidence of the high-risk involvement of youth in automobile crashes, the effects of alcohol in young adults need to be more thoroughly examined by cognitive studies, and more direct preventive solutions need to be taken focusing on this age range.