Harm to some elicits greater sympathy than harm to others. Here, we examine the role of posterior medial frontal cortex (PMFC) in regulating sympathy, and explore the potential role of PMFC in the related phenomena of mentalizing and representing others as connected with oneself. We down-regulated either PMFC or a control region (middle temporal visual area), then assessed feelings of sympathy for and self-other overlap with two characters described as having suffered physical harm, and who were framed as adversarial or affiliative, respectively. We also measured mentalizing performance with regard to inferring the cognitive and affective states of the adversarial character. As hypothesized, down-regulating PMFC increased sympathy for both characters. Whereas we had predicted that down-regulating PMFC would decrease mentalizing ability given the postulated role of PMFC in the mentalizing network, participants in the PMFC down-regulation condition evinced greater second-order cognitive inference ability relative to controls. We observed no effect of the TMS manipulation on self-other overlap, although sympathy and self-other overlap were positively correlated. These findings are discussed as they may inform understanding of the functional role(s) of PMFC in regulating responses broadly linked with empathy.