The post-Olympic period is a challenging and stressful period in which many athletes can experience a range of negative psychological reactions. This has led to the coining of the term ‘post-Olympic blues.’ The purpose of this study is to explore the post-Olympic mental health of Danish athletes with the specific aim to investigate the number of Danish athletes experiencing ‘post-Olympic blues’ after the Tokyo Olympics. Forty-nine Olympic athletes completed measures of well-being (Short-Warwick-Edinburg-Mental-Wellbeing-Scale), depression (Patient-Health-Questionnaire-9), and anxiety (Generalized-Anxiety-Disorders questionnaire) one month after the Olympics Games.  The results indicated that 27% of athletes reported either below average well-being or moderate to severe depression scores, with 16% reported both below average well-being and moderate to severe depression scores. Female athletes reported significantly higher depression than male athletes, with no significant gender difference in well-being or anxiety. No significant age differences were found. No statistically significant results were found between athletes’ goal achievement and mental health, however, there was a tendency that athletes who failed to meet performance expectations reported more negative experiences post-Games. The current results are discussed with regards to developing a clear definition of post-Olympic blues, practical implications, and future research.