ABSTRACT. Objective: Level of response to alcohol has been associated with risk of alcohol dependence in a number of ethnic groups. In the present study, subjective and objective responses to alcohol were evaluated in Indo-Trinidadians (Indo-T) and Afro-Trinidadians (Afro-T). Associations of alcohol dehydrogenase polymorphisms with response to alcohol, using the Subjective High Assessment Scale (SHAS), and breath alcohol concentrations (BrAC) were tested. Method: Regular male drinkers without alcohol dependence (n = 112) ages 18-25 years participated in alcohol challenge sessions consisting of placebo and two doses of alcohol (target BrAC: 0 g/dl for placebo, .04 g/dl low dose, and .08 g/ dl high dose) and genotyped for variants in ADH1B*3 and ADH1C*2. Results: Indo-T had signifi cantly higher BrAC, pulse rates, and cortisol levels when compared with Afro-T but did not have signifi cantly higher SHAS values. Higher responses on the SHAS items muddle/confused and nauseated were signifi cantly associated with the presence of at least one ADH1B*3 allele following the high dose of alcohol in Afro-T. Indo-T with at least one ADH1C*2 allele displayed signifi cantly different Drug × Time interactions for the SHAS item effects of alcohol at the low dose and for the SHAS items clumsy, muddle/confused, effects of alcohol, fl oating, drunk, and total at the high dose from Indo-T with two ADH1C*1 alleles. Conclusions: This is the fi rst study that has investigated individual sensitivity to alcohol in a Caribbean population and in people of East Indian descent. Indo-T with at least one ADH1C*2 allele may be at higher risk for heavy drinking by feeling less of the effects of alcohol, including nausea. In Afro-T, having at least one ADH1B*3 allele appears to exert a protective effect by enhancing the unpleasant effects of alcohol, such as nausea and confusion. (J. Stud. Alcohol Drugs, 75, 827-838, 2014)