The paper concerns the problem of mood structure. In the theoretical part definitional problems and topics of discussion held in recent years on different structural models of mood are presented. as well as arguments supporting a three-dimensional model of the mood. The research carried out is consistent with the model that comprises three correlated mood dimensions: tense arousal, energetic arousal and hedonic tone. The results obtained indicate a relationship of the three mood dimensions with anxiety, neuroticism and positive and negative affect. The direction of this relationship to some extent confirms correctness of the scale. No expected relationships with extraversion were found. The data concerning the reliability and theoretical (and factorial) correctness confirm that the Polish adaptation of the UMACL does not depart from the original version as far as psychometric parameters are concerned. The research shows that the scale is sensitive to changing mood patterns in subjects with mood disorders (diagnosed depression). Sex differences related to the three mood dimensions turn out to be ambiguous.