Rules are often installed in order to constrain unethical behavior. Rules can be framed either in specific ("Don't accepts gifts from clients.") or general terms ("Don't engage in conflicts of interest."). The current investigation examines the effect of specific and general rules on unethical behavior and how this effect depends on personal gain resulting from the unethical behavior. The results of three preregistered experiments suggest that both specific and general rules counteract the increase in unethical behavior induced by high personal gain. Although the results were not fully consistent across all studies, specific rules appear more successful in doing this than general rules. In Studies 1 and 3, when personal gain from unethical behavior was (extremely) high, specific rules were more successful in reducing unethical behavior than were general rules. Results of Study 2 suggest that the larger effect of specific rules (compared to general rules) is caused by specific rules preventing people from engaging in moral rationalizations that justify their unethical behavior. A meta-analysis across all studies confirms this overall pattern. This research contributes to theory on rules, ethical codes, and the influence of personal incentives from unethical behavior.