Ghoul, N, Tabben, M, Miarka, B, Tourny, C, Chamari, K, and Coquart, J. Mixed martial arts induces significant fatigue and muscle damage up to 24 hours post-combat. J Strength Cond Res 33(6): 1570-1579, 2019-This study investigates the physiological/physical responses to a simulated mixed martial arts (MMA) competition over 24 hours. Twelve fighters performed a simulated MMA competition, consisting of three 5-minute MMA matches. Physiological/physical data were assessed before (Trest), directly after round 1 (Trd1), round 2 (Trd2) and round 3 (Trd3), and then 30 minutes (Trecovery30min) and 24 hours (Trecovery24h) post competition. Heart rate (HR), rating of perceived exertion (RPE), and blood lactate concentration ([La]) were assessed at Trest, Trd1, Trd2, and Trd3. Biological data were collected at Trest, Trd3, Trecovery30min, and Trecovery24h. Physical tests were performed at Trest, Trecovery30min, and Trecovery24h. HR, RPE, and [La] were high during competition. Leukocytes, hemoglobin, total protein, and glycemia were increased at Trd3 compared with all other time points (p ≤ 0.05). Cortisol was increased at Trd3 compared with Trest and Trecovery24h (p ≤ 0.05). Testosterone was higher at Trd3 and Trecovery30min than Trest (p < 0.001). Higher values of uric acid were noted during recovery periods (p < 0.001). Lactate dehydrogenase was lower at Trest compared with Trd3, Trecovery30min, and Trecovery24h (p ≤ 0.05). Countermovement jump was higher at Trest than Trecovery30min (p = 0.020). Consequently, MMA is a high-intensity intermittent combat sport that induces significant fatigue and muscle damage, both of which are still present at 24 hours post competition.