Deceiving others is generally viewed as immoral. However, most people lie on a daily basis. This article examines the psychological consequences for the liars themselves, as they are participating in what is generally perceived as immoral behaviour. More specifically, this article focuses on the effects of lying on the liar's self‐esteem and affect. We tested if lying, in comparison to telling the truth, lowers people's self‐esteem and increases negative experienced affect. In total, three cross sectional and one longitudinal studies were conducted (N = 783). Results showed that lying decreased people's self‐esteem and increased negative affect, regardless of the type of lie (self‐centred vs. other‐oriented). Furthermore, lying on a given day decreased people's self‐esteem compared to their self‐esteem on the previous day and to their average level of self‐esteem across 5 days.