Purpose– The purpose of this paper is to study how relationship marketing can reduce cognitive dissonance in post-purchase stage and, thereby, increase customer satisfaction and encourage loyalty under mediating roles of trust and cognitive dissonance.Design/methodology/approach– Based on a survey on consumers of cell phones, the authors tested the effects of relationship marketing on cognitive dissonance and then customer satisfaction, behavioural, and attitudinal loyalty, using structural equation modelling.Findings– The results indicate that, thanks to relationship marketing, consumers undertook less cognitive dissonance in post-purchase stage. Thus, as consumers faced less cognitive dissonance, they represented more satisfaction and thereby behavioural and attitudinal loyalty. Additionally, the study confirmed the mediating role of trust and cognitive dissonance.Practical implications– The results show that when brands and retailers make their ties with their customers stronger and encourage trust, they can discourage cognitive dissonance in post-purchase stage and thereby encourage customer satisfaction and behavioural and attitudinal loyalty.Originality/value– Literature on post-purchase behaviour and cognitive dissonance shows how cognitive dissonance can reduce post-purchase satisfaction. Our research adds to the literature of both relationship marketing and post-purchase behaviour.