There is increasing interest in the role of striatal dopaminergic activity in social approach–avoidance motivation. The 9-repeat allele of the dopamine transporter (DAT) gene, associated with increased striatal dopamine levels, has been found to be related to increased sensitivity to reward. However, it remains unexplored whether this polymorphism influences automatic action tendencies in the social domain. We set out to test experimentally whether human carriers of the 9-repeat allele show increased approach–avoidance tendencies compared to non-9-repeat carriers. One hundred and one healthy adults, genotyped for the DAT gene, performed the social Approach–Avoidance Task, a reaction time task requiring participants to approach or avoid visually presented emotional (happy and angry) faces, by pulling a joystick towards them or pushing the joystick away from themselves, respectively. In accordance with expectations, 9-repeat carriers showed stronger approach–avoidance effects compared to non-9-repeat carriers. These results suggest a role for striatal dopaminergic polymorphisms in motivational responses to social-emotional cues. Our findings may be relevant in the selection of candidate genes in future studies involving social behavior.