The professor of pharmacy, Johann Georg Noel Dragendorff (1836-1898) is primarily known in the history of pharmacy as a pharmacognosist and forensic chemist, so far he has been less described as a toxicologist. He worked for 30 years (1864-1894) at the University of Dorpat (Tartu) in Estonia, and had been invited from Germany, developing here one of the pharmaceutical research centers in all of Europe. Dr. Dragendorff supervised 90 theses of Master of Pharmacy and 87 theses of Doctor of Medicine in Tartu/Dorpat. Dragendorff's supervised master's theses reveal his particular interest in phytochemistry. Of the 87 doctoral dissertations supervised by Dragendorff, are related to forensic chemistry (26 works), and toxicology with pharmacology (21). This work introduces Dragendorff as a toxicologist, discusses the theses supervised by him and his textbooks. Dragendorff's development as a toxicologist was logical considering his extensive scientific activities and the drugs characteristic of the 19 th century. These, especially alkaloids and mercury preparations, are introduced in more detail in this study.