Introduction: Research investigating the physiological demands of dance performance has documented exercise intensity and time spent in work and rest; however, available data are across limited dance genres and often use rehearsal or simulated conditions. Real-time data recorded during live performance with an audience are limited. The aim of the study is to provide a detailed description of the physiological demands of live professional Irish dance performance. Method: The entire Irish dance cast of Riverdance participated in the study (n = 24). Approval was granted by the Institutional Research Ethics Committee. Matinee and evening performances on the first day of a tour were examined in a descriptive, cross-sectional design. Heart rate (HR) monitors worn discretely under costumes recorded data every 5-seconds. Video analysis allowed calculation of time spent in work and rest. All descriptive analyses were split by role (troupe/lead) and sex (male/female). Results: Dancers worked at hard/very hard intensities (mean > 72%, peak > 91% HR max ) for ~3 minutes at a time for 3-9 individual dance numbers. There was a high variation in overall demand experienced by individual dancers due to variation in both duration and intensity of on-stage time, dependent upon their role. Mean total on-stage time was 18.18 ± 5.82 minutes, 19.43 ± 5.80 minutes, 29.71 ± 0.62 minutes, 20.00 ± 0.00 minutes for male troupe, female troupe, male lead, and female lead dancers, respectively. Recovery periods were varied in terms of duration, activity undertaken, and HR response. Conclusion: Individual dance numbers within a professional Irish dance show were high intensity for a short duration when considered in isolation, but overall physiological demand experienced by any one dancer across the entire show varied dependent upon their role and off-stage/recovery practices. Future research investigating the physiological demands of dance performance should ensure analysis accounts for the individual dancer's role and should capture the entire show duration in repeated exposures., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.