Oxytocin (OT) and a polymorphism (rs53576) in the oxytocin receptor gene (OXTR) have been independently associated with stress reactivity, whereas oxytocin's sister peptide, arginine vasopressin (AVP) and polymorphisms in the vasopressin receptor gene (AVPR1A) have been independently associated with aggressive behavior. In this study, 68 men and 98 women were genotyped for the OXTR rs53576 polymorphism and the AVPR1A RS1 polymorphism. Baseline and poststressor levels of plasma OT, plasma AVP, positive affect, and anger were assessed. Women, but not men, with high levels of poststressor OT and the GG genotype of rs53576 felt the most positive affect after the stressor. Men, but not women, with high levels of poststressor AVP and the 320 allele of the RS1 polymorphism reported more poststressor anger than noncarriers. These data constitute the first evidence that oxytocin and vasopressin receptor genes interact with levels of OT and AVP to predict sex-specific emotional stress responses.