Exertional heat stroke (EHS) is a medical emergency characterized by life-threatening hyperthermia and central nerve system dysfunction during or directly after exercise. Early recognition and aggressive cooling reduces morbidity and mortality of patients with EHS. Therefore, all health care professionals involved in acute care should immediately recognise EHS and start cooling with cold water immersion as soon as possible. Most EHS occur in young and healthy individuals without a medical history, such as athletes or soldiers. We report the case of EHS in a 26-year-old man without a medical history. He suffered from EHS during a military admission test. A few years later he had a second EHS during military training. This time, the EHS was complicated by compartment syndrome, rhabdomyolysis, acute kidney injury and epilepsy. He fully recovered from both EHS episodes. Muscle histology, whole exome sequencing and heat tolerance tests did not show any abnormalities.