We study gender differences in altruism in a large random sample of the Swedish population using a standard dictator game. Beside a baseline treatment we implement a priming treatment where participants are reminded of their gender, and two treatments with known male and female counterpart respectively. We find suggestive evidence that women are more altruistic than men only in the priming treatment. A post-hoc analysis using data on interviewer gender to explore gender context effects indicates that priming affects behavior only in mixedgender contexts.