Vasopressin is a neuropeptide that has been strongly implicated in the development and evolution of complex social relations and cognition in mammals. Recent studies in voles have shown that polymorphic variation in the promoter region of the arginine vasopressin V1a receptor gene (avpr1a) is associated with different dimensions of sociality. In humans, variation in a repetitive sequence element in the 5′ flanking region of the AVPR1A, known as RS3, have also been associated with variation in AVPR1a gene expression, brain activity and social behavior. Here, we examined the association of polymorphic variation in this same 5′ flanking region of the AVPR1A on subjective ratings of personality in a sample of 83 chimpanzees (Pan troglodytes). Initial analyses indicated that 34 females and 19 males were homozygous for the short allele, which lacks RS3 (DupB−/−), while 18 females and 12 males were heterozygous and thus had one copy of the long allele containing RS3 (DupB+/−), yielding overall allelic frequencies of 0.82 for the DupB− allele and 0.18 for the DupB+ allele. DupB+/+ chimpanzees were excluded from the analysis because of the limited number of individuals. Results indicated no significant sex difference in personality between chimpanzees homozygous for the deletion of the RS3-containing DupB region (DupB−/−); however, among chimpanzees carrying one allele with the DupB present (DupB+/−), males had significantly higher dominance and lower conscientiousness scores than females. These findings are the first evidence showing that the AVPR1A gene plays a role in different aspects of personality in male and female chimpanzees.