OBJECTIVE: In high-performance sport, the use of self-report measures is expanding. The exploration of wellness states in response to training and performance requires further investigation for professional ballet dancers and athletes. This study therefore aimed to: compare wellness scores between professional ballet dancers and athletes in training and performance; report frequency of self-reported modified participation during training and performance; and report frequency of self-reported inability to participate due to pain and illness in dancers and athletes. METHODS: Fourteen professional ballet dancers (mean 26 yrs, SD 2.6) and 14 sex- and age-matched professional athletes (mean 27.7 yrs, SD 2.9) recorded daily wellness (fatigue, stress, sleep quality and quantity), participation (full, rest, modified, or unable to participate) and activity (performance, training) into a wellness application on their smart phone over a 4-month period. Mixed factorial ANOVAs were conducted to assess the interaction between group (ballet dancers and athletes) and activity (performance and training) on the dependent variables (stress, fatigue, sleep quality, and sleep quantity). RESULTS: Stress and fatigue levels were higher for both dancers and athletes during performance compared to training periods. Dancers recorded lower sleep quantity than athletes, with no difference in sleep quality. Modified participation appears more common in dancers compared to athletes. Dancers and athletes were rarely unable to train or perform/compete over the 4 months. CONCLUSION: Self-reported wellness scores appear sensitive to activity type and can provide valuable information to guide intervention and recovery strategies. Further research on the impact of poor wellness on performance, illness, and injury in professional ballet is warranted.