First Serbian works on Theory of Relativity ​Žarko Mijajlović​ , Nadežda Pejović​ , Viktor Radović​ Faculty of Mathematics, Univ. of Belgrade, Serbia Even if A. Michelson, H. Lorentz, H. Poincaré and others performed experiments and wrote papers to the subject known later as the special theory of relativity more than two decades before Albert Einstein published his paper on this topic in 1905, it is usually considered that special theory of relativity originated in this year. This theory was soon accepted and many authors wrote papers on this matter. ​It is not so well known that several Serbian mathematicians and astronomers also wrote papers on special theory of relativity already in the twenties of XX century. Some of the papers were popular explanation of basics of this theory and they were intended to the general public, but there were also papers with original contributions. All papers were written in Serbian and certainly this is the main reason that these results were neglected. We shall present works in this field of a great Serbian astronomer and climatologist Milutin Milankovć (1879-1958), a great Serbian mathematician and the founder of the Serbian mathematical school Mihailo Petrović Alas (1868-1943) and Sima Marković (1888-1939), mathematician, philosopher and politician, also known as one of the founder of the Communist Party of Yugoslavia.