Background Although classic heat exposure and heat stroke is one of the most ancient conditions known to humans, the description of its early clinical manifestations, natural course, and complications remains uncertain. Heat exposure and heat stroke is a life-threatening condition characterized by a rapidly increasing core temperature above 40°C and neurologic alterations, such as delirium, convulsions, or coma, after exposure to extreme environmental heat alone or in combination with intense physical exertion. Heat-related illnesses (HRIs), such as heatstroke (HS) and heat exhaustion (HE), are common complications during Hajj pilgrims. The Saudi Ministry of Health (MOH) developed guidelines on the management of HRIs to ensure the safety of all pilgrims, must be healthcare workers’ (HCWs) adherence to the updated national guidelines regarding pre hospital and in-hospital management of HRIs. Aim of the study: To influence of Knowledge of Healthcare Workers about Hazards of Heat Exposure and Prevalence of Heat-related illnesses among pilgrims attending at hospitals and primary health centers in Makkah at Saudi Arabia 2022. Methods: Across sectional descriptive study conducted among Healthcare Workers about Hazards of Heat Exposure and Prevalence of Heat-related illnesses among pilgrims attending at hospitals and primary health centers, Makka, June, 2023 to July 2022 Hajj 2022, Our total Sample size of health care workers participants were (200) Results: the relation of Knowledge of the healthcare workers about hazards of heat exposure and Prevalence of heat-related illnesses among pilgrims regarding the knowledge the most of participants average knowledge were (56.0%) followed by high were (26.0%) but weak were (18.0%) and total were (100.0%) while heave a significant relation were P-value <0.001 and X2 48.16 Conclusion: Heat Exposure and Heat Illnesses are not common problems among Saudi Arabians. They are, however, of significance in pilgrims from other parts of the world during Haj season, which varies according to the lunar calendar year. In recent years, Haj has coincided with the summer months of July and August. The temperatures during Haj reach an average high of 54°C (130°F).