Many witnesses to violent crimes are alcohol intoxicated, but research is lacking regarding how alcohol affects their perception of aggression and guilt. This study investigated to what extent alcohol intoxicated eyewitnesses differed from sober witnesses regarding how aggressive and guilty they perceived the involved parts in an intimate partner violence (IPV) situation. Eighty-seven healthy men (n = 44) and women (n = 43) were randomized to an alcohol group (0.7 g/kg) or a non-alcohol group. In a laboratory setting, alcoholic/non-alcoholic drinks were consumed before viewing a film depicting IPV between a man and a woman. Ten min after viewing, in an interview, the participants rated how aggressive and guilty they perceived the involved parts to be. Alcohol intoxicated participants perceived both parts’ physically aggressive behavior as comparatively less severe, but their neutral behavior as more hostile. Sober witnesses perceived the man to be the most guilty part, whereas intoxicated witnesses distributed guilt more evenly. Alcohol had a strong but complex impact on the perception of aggression in IPV (i.e., heightened during the neutral interaction and lowered during physical aggression). These results may be explained by the cognitive consequences of alcohol’s anxiety-dampening effects. Regarding the asymmetric difference in perceived guilt, stereotypical expectations of gender-appropriate behavior in an IPV situation may need to be considered.