Using social exchange theory, this paper investigates the antecedents of supplier unethical practices on continuity of buyer-supplier relation and its consequence on firm performance. The analysis of 130 informants from public entities in Tanzania, the results indicates that two supplier's unethical practices have significant impact on the continuity of buyer-supplier relation which include corruption and supplier deceitful. Using the mediating role continuity of buyer-supplier relationship, the study indicates that corruption and deceitful affect the firm performance (quality and delivery). The research conclude that the public entities should be very careful on the effects of unethical practices on continuity of relationship and managers in public organizations should not take for granted particularly the corruption practices and deceitful. This study provides insightful contribution to practitioners and researchers intended to conducted research on ethical supply chain.