Driving/riding under the influence (DUI) of alcohol is a major public concern worldwide. Only a few studies have distinguished DUI-related variables between motorcyclists and car drivers. This study examined the differences in demographic characteristics and drinking behaviors among first-time DUI offenders operating different transportation vehicles, and risk factors for frequent DUI (fDUI) among them.We conducted an anonymous survey for 561 first-time DUI offenders who attended a mandatory educational program. Participants self-administered questionnaires concerning alcohol drinking behaviors and DUI. We defined fDUI as at least two DUI behaviors per month based on self-reported information. Demographic and drinking characteristics were compared between DUI offenders, car drivers and motorcyclists. Logistic regression analysis was used to examine risk factors for fDUI.Two-thirds of first-time DUI offenders were motorcyclists. Compared with car drivers, motorcyclists were younger and less educated, with a higher percentage of them being women and unmarried. Car drivers reported a higher rate of fDUI than motorcyclists (16.5% vs. 9.7%). Regression analysis revealed that binge drinkers had a higher fDUI risk in both groups. Regarding the drinking place prior to DUI behavior, workplace was significantly associated with fDUI in car drivers.Distinct strategies may be required for motorcyclists and car drivers for DUI recidivism prevention, and drinking place interventions should also be considered.