The work “Fava’id al-Hikmat” (“Treasure of Wisdom”) by Haji Suleyman Qajar Iravani (18th century), a prominent Azerbaijani physician and scientist, a native of Iravan, written in the Persian language has gained great fame not only in Azerbaijan, but also in Central Asia and Iran. This book is an encyclopaedia of medieval pharmaceutics which tells about healing properties of thousands of medicinal plants, animals and minerals. The book consists of two parts. The first part contains an alphabetical list of medicines with a description of their properties, composition and methods of preparation. The second part is an explanatory dictionary of medieval pharmaceutical terms. It contains names of plants, animals and minerals in the Azerbaijani, Turkic, Arabic, Persian, Greek, Chinese, Indian and other languages. Rare manuscript copies of “Fava'id al-Hikmat” are kept at the Institute of Manuscripts named after Muhammad Fuzuli of Azerbaijan National Academy of Sciences, as well as in Iran and Egypt.