This article is concerned with mood level rhythm over the day. In the study mood was measured in the course of a day using the UMACL scale and the participants' chronotype was assessed. Daily variation was found in all three mood dimensions, but each had its specific course. Morning hours turned out to be especially disadvantageous in terms of the hedonic tone and tense arousal levels. Energetic arousal exhibited the highest values at midday in the morning type subjects and in the evening in the evening type subjects. The results suggest that from the chronopsychological point of view it was justified to distinguish the three mood dimensions. Another very important conclusion is that the hour of measurement should be controlled for each of the three mood dimensions both in further research and in psychological practice.