This experimental research investigated if there are economic and social sanctions (i.e., backlash) for counter-stereotypically behaving, angry females in computer-mediated negotiations. Participants (N = 82) received angry or joyful chat messages from their ostensible male or female opposite (i.e., a computer program). Results confirm the well-known anger effect: Participants demanded lower points for themselves when negotiating with an angry vs. joyful opposite. Moreover, participants liked the angry opposite less, perceived them as less competent and more competitive. However, the opposite's gender did not moderate these findings, although exploratory evidence for a backlash effect emerged: Angry females had descriptively lower negotiation outcomes, were liked less and perceived as significantly more competitive than angry males. These results suggest that when studying negotiations in human-agent interactions, both emotions and gender should be considered as important factors driving negotiation results and social perceptions of the agent.