UNLABELLED: This work presents the results of research into the life and work of Dr. Stanko Sielski, related to his professional, scientific and humanitarian work. He was born in Gracanica, Bosnia and Herzegovina (BH) in 1891, to a family of Polish origins. He attended high school in Travnik and completed his studies of medicine in Vienna in 1919. During the First World War he served on the frontlines with the Austro- Hungarian army. He began his service as a doctor in Konjic, Prozor and Glamoc, and then worked in Varcar Vakuf, Zenica, Travnik, Bihac, Banja Luka, Sarajevo and Tuzla. At that time in BH living conditions were very bad, the level of education of the people insufficient, there were many epidemics of infectious diseases, and the mortality of the population was high. Dr. Stanko Sielski made a significant contribution to treating the sick, preventing various diseases and the health education of the people. In the realm of the history of medicine in BA, he researched the life and work of doctors from previous generations, the work of medical institutions, old medical manuscripts written in Arabic, Persian and Turkish, folk beliefs about the origins and treatment of a variety of illnesses, and the role of herbal medicine and amulets in treating the sick. In addition, he undertook research in the fields of archaeology, ethnology and sociology. He published the results of his research in scholarly journals. In the Second World War he saved the lives of many Jewish doctors and their families from persecution in concentration camps, and as a result in 2014 he was posthumously declared "Righteous Among the Nations". CONCLUSION: Dr. Stanko Sielski, alongside his work as a doctor, was also involved in a variety of scientific research and publication work, which contributed to the preservation and a better understanding of the material and spiritual heritage of BH.