The duration of the longevity of Imam Mahdi’s life has been an area of disagreement among several Sunni and Shi‘i scholars. The findings of this research are based on the Qur’anic verses, Shi‘a and Sunni hadith, biological and medical law, and historical documents. These findings reveal that it is possible to live an exceedingly long life, as the Prophet Noah, the Men of the Cave, and Prophet Khidr are among those who have done so.