Physicists and chemists were among the first potential victims of occupational exposure to ionising radiation and they were also the first to warn about the harmful effects of radiation on living organisms. This review presents the work of the first notable scientists in the field of radiation science in Croatia from the discovery of radiation (Henry Becquerel in 1896) to 1945. The beginning of radiation science and radiation protection in Croatia can be traced to the end of the 19th century. Our research of the archived material and literature not only gave a deeper insight to the life and work of some of these notable scientists, but also gave a glimpse of previously unknown facts and details important for the history and development of radiation science, radiation protection, as well as medical physics. Our research has shown that Croatian scientists not only kept pace with contemporary scientific knowledge but also made notable contributions from the very beginning.