The accumulation of fraud scandals in the banking industry has spurred a controversial policy debate about the role of professional culture in unethical business practices among bank employees. We conducted an experiment with employees from an internationally operating bank to identify the causal effect of professional culture on dishonesty. We exogenously increased the saliency of bank employees’ professional identity and subsequently measured their dishonesty in a task in which they could manipulate their payoffs without any danger of being detected and sanctioned. Our results show that bank employees in the control treatment behave mostly honest, but cheat significantly when their professional identity is made more salient. We conducted two placebo experiments with non-banking managers and students demonstrating that the observed treatment effect is specific to people from the banking industry. Taken together, these findings suggest that the professional culture in the banking industry breeds dishonest behavior.