PurposeThis study aims to examine the relationships among senior managers’ reports of bribery practices, ethical awareness and firm productivity in Thailand. Bribery pervasiveness is examined as moderating the relationship between bribery practices and ethical awareness. Ethical awareness is examined as a mediating effect of bribery practices and managerial perceptions of firm productivity.Design/methodology/approachThis study uses a mixed-method approach consisting of interviews with more than 20 senior managers and surveys collected from more than 200 senior managers in Thailand’s manufacturing and construction industries. Hierarchical regression is used to test the hypotheses.FindingsSenior managers report that their firms are more likely to flout ethical principles when they perceive that their industries feature widespread bribery practices. However, the tests fail to support the hypothesis that the flouting of ethical principles leads to less productivity.Originality/valueThis study contributes to transaction cost economics theory by extending the concept of illegal transaction cost minimization to managerial perceptions of firm productivity. This study also integrates research on bribery rationalization by considering how managerial rationalization and justification of bribery practices impact managerial perceptions of firm productivity and ethical awareness. This research provides managers with an understanding of how attitudes toward ethical conduct and unethical actions impact perceptions of firm productivity.