The present study was conducted in an attempt to replicate previous findings regarding relations between personality domains in the five-factor model of personality and drinking motives, and to examine the potential mediating role of the internal drinking motives in explaining hypothesized relations between personality variables and drinking quantity/drinking problems. A sample of 154 university student drinkers completed the NEO five factor inventory, the revised drinking motives questionnaire, and measures of drinking quantity and alcohol-related problems. Multiple regressions indicated that the two internal drinking motives (coping and enhancement) were predicted by personality domains information, whereas the two external drinking motives (conformity and social) were not. Coping motives were significantly predicted by high neuroticism, whereas enhancement motives were significantly predicted by a combination of low conscientiousness and low neuroticism. Mediator regression analyses demonstrated that coping motives partially mediated the relation between high neuroticism and increased drinking problems, whereas enhancement motives mediated the relation between low conscientiousness and increased drinking quantity. Implications of the findings for prevention of heavy drinking and drinking problems in young adults are discussed.