Destruction of Iranian scientific works through foreign invasions led to the depletion of scientific treasures of our famous scholars, which had long played a great role in the advancement of sciences. Many later researches have also ignored the contribution of Iran to such advancements. Studying the book “Al-Hawi,” we encounter the name of many people and books, which are not considered in any medical history book. In order to explore, their works, and their role in medical and pharmaceutical development, the 23 volumes of Al-Hawi (organized in 24 books) were carefully investigated. Among these scholars one encounters an individual under the assumed name of “Majhul,” whom Rhazes quoted on 208 instances from one line to multiple pages. By analyzing the citations, it was concluded that “Majhul” must have been an Iranian who probably lived in the 7th century. Rhazes was greatly influenced by Majhul from the scientific point of view, and agreed with him in most of the cases, using allusions such as “great, expert, or trust him” showing recognition towards Majhul’s scientific rank. Majhul was the first to use cotton in medicine. He called nyctalopia as “ruz kur” (which means blind in the day), and considered the types of cataract which require surgery. He was the first to identify errors in Galen’s works and by criticizing Galen, established a new era in medical research.