The aim of the study was to examine the relationship between self-esteem and perceived parental favoritism, and the difference in correlations with regard to gender and birth order. The sample included 47 pairs of same-gender siblings. Participants filled out the scales for the assessment of the perceived parental favouritism and self-esteem. The results showed that the last-born children both perceived themselves and were perceived as more favoured by both mother and father. There were no gender differences in the perception of parental favouritism. Furthermore, men have higher levels of self-esteem, where first-born men have higher levels of self-esteem than second-born men, first-born and second-born women. Associations between perceived parental favoritism and self-esteem were not found. Two hierarchical regression analyses were conducted, one for the independent variable maternal favoritism and the other for the independent variable paternal favoritism. The criterion variable in both cases was self-esteem. We examined the moderating effect of gender and birth order on the association between parental favouritism and self-esteem. Women who perceived higher maternal favouritism had higher self-esteem than women who perceived lower maternal favouritism. Men have higher self-esteem than women regardless of perceived maternal favoritism. For fathers' favouritism, no differences were found in the level of self-esteem.