Mass gatherings are events such as religious occasions, music festivals, or sports events that attract enough people to exceed the capacity of routine health and public safety measures. Managing such events requires providing for all eventualities from infectious disease outbreaks to security against terrorist attacks. Thus, mass gatherings health is a topic that goes beyond the scope of typical public health provision and becomes an indispensable speciality under special domain specially relevant to Public health issues in Saudi Arabia due to annual mass gathering events like Hajj and umrah. A vulnerable population is a group of individuals who are at increased risk for health problems and health disparities. Examples of vulnerable populations are the very young and the very old, individuals with chronic illnesses, disabilities, or communication barriers and veterans. Therefore, awareness and knowledge about those included in vulnerable populations is essential to utilize the associated resources available to promote health equity and reduce health disparities in this population.