How does single-party dominance influence interpersonal trust? We draw on evidence from trust games played by more than 2,000 subjects in South Africa, where, since Apartheid, race-based social enmity has persisted under democratic competition characterized by single-party dominance. We find that partisan-based trust discrimination is most pronounced for those who identify with the main opposition party and is driven by strong distrust of rival partisans. These findings underscore how electoral competition, in general, shapes trust across party lines and suggests one-sided competition, in particular, has asymmetrical effects between parties in dominant party systems. Moreover, this study provides additional evidence regarding the relative weights of trustworthiness stereotypes tied to partisanship and race.