The current study tested whether experimentally induced social comparisons affect mood and self-esteem in euthymic unipolar and bipolar patients, compared to participants without any history of affective disorders. It was predicted that unfavourable upward comparisons with feedback that another person was performing better would have a negative effect on implicit self-esteem and explicit mood (positive and negative affect) in unipolar patients. We further predicted that favourable downward social comparisons with feedback that another person was performing worse will enhance mood and self-esteem, especially in bipolar patients. Participants were randomly assigned to upward or downward social comparison in a brainstorming task. As was expected, after upward comparison, negative affect increased, whereas positive affect decreased in all groups. After downward comparison, positive affect initially increased in unipolar and healthy subjects, while in bipolar patients no significant change in positive affect was observed. Implicit self-esteem generally showed an unexpected decrease regardless of the comparison condition and group. Remitted bipolar patients seemed to be less sensitive to positive feedback which may reflect ‘dampening’ of positive affect which has been observed before in bipolar patients.