Dr. Sayed Ridha al-Hajjar was born in the holy city of Najaf, Iraq, in 1940. After graduating from medical school in Baghdad, he came to the United States of America to further his education. Where he eventually got his degrees in Internal Medicine and Endocrinology. In the early years he was active in the Islamic Society of Orange County eventually serving as President. In 1989, Dr. al-Hajjar along with other Iraqi-American community members founded the Ahlulbayt Mosque in Pomona, where he served as an Imam until his final days.

Dr. Sayed Ridha al-Hajjar was known for his great humility, asceticism and dedication to serving the Muslim community of Southern California. As a physician by profession, Dr. al-Hajjar spent much of his time compassionately tending to the medical needs of the community. He never hesitated in providing care for those in need. Additionally, Dr. al-Hajjar was a religious leader and spent over three decades serving the Muslim community in Southern California, especially the Iraqi-American community.