Exertional heat stroke (EHS) and Malignant Hyperthermia (MH) are potentially lifethreatening conditions with overlapping clinical characteristics. In this study, we compared the thermoregulatory response to exercise under increased environmental temperatures in individuals with a history of EHS (n = 15) or MH (n = 14) to healthy controls (n = 15). Groups were age- and sex-matched (31 male, 13 female, 42 ± 10 years). A 60-min exercise test was performed on a cycle ergometer at an ambient temperature of 30.3 ± 0.6°C and a relative humidity of 33.5 ± 4.7%. A stepwise incremental exercise protocol was used to reach a metabolic heat production of 6, 8 and 9 W/kg body mass. Gastrointestinal (Tgi) and skin (Tsk) temperature were monitored continuously, and partitional calorimetry was used to calculate dry (Hdry) and respiratory heat loss (Hresp). Whole-body sweat rate (WBSR) was assessed by measuring body mass. Exercise-induced increases in Tgi (1.4 ± 0.5°C) and Tsk (1.9 ± 0.8°C) were observed, but the magnitude of increase across groups was comparable (ptime*group = 0.80 and p = 0.57, respectively). Hdry was significantly lower in EHS participants (54 ± 4 W) compared to controls (65 ± 11 W, p = 0.023). No differences were observed in Hresp and WBSR. Our results suggest that individuals with MH or a history of EHS do not have an altered thermoregulatory response to exercise in the heat in a controlled setting. Further research is required to determine to what extent the complex accumulation of risk factors contributes to EHS susceptibility.