This thesis provides an overview of one of the greatest discoveries of the Croatian chemical science, synthesis of azithromycin by Pliva (1981). The development of the pharmaceutical industry in Croatia began with establishment of joint stock company and the company "Kaštel" (1920), which about twenty years later merged with the National Institute for the production of medicines and vaccines and continues to operate under its current name "Pliva" (1942). With establishment of Pliva's Research Institute (1952) began scientific research aimed at developing new drugs. The discovery of azithromycin, broad-spectrum macrolide antibiotic, is the biggest success in the history of Pliva and Croatian pharmaceutical industry. It was created as a product of several years of work on new chemical compounds, in particular the derivatives of erythromycin A. Its discovery is credited to the research team of the Research Institute Pliva: Gabrijela Kobrehel, M.Sc., Gorjana Lazarevski, Ph.D., Zrinka Tamburašev, Ph.D., with their research team leader Slobodan Đokić, Ph.D. Azithromycin has become a basis for the development of new macrolide antibiotics, later called azalides as well as extensive research in the field of azithromycin chemistry that resulted in a large number of Pliva patents and scientific papers. Pliva has put finished drug on the market in partnership with the US pharmaceutical company Pfizer. Under the brand name Sumamed (PLIVA) and Zithromax (Pfizer), azithromycin has become one of the best-selling antibiotics on a global level due to the extremely successful therapeutic effects.