E. Lejnieks was born on the 19th of May, 1889, in Riga. From 1900 to 1907 he studied in Riga Peter the 1st School. He continued studies at Moscow University and graduated cum laude from Faculty of Mathematics in 1911. He was asked to stay at the Faculty and to become a lecturer and a researcher; in 1913 he obtained the degree of Master of Mathematics. Lejnieks returned to Latvia in 1919 and was one of the founders of Faculty of Mathematics and Natural Sciences at the University of Latvia. In 1920 E. Lejnieks was elected a Professor and the first Dean of Faculty of Mathematics and Natural Sciences (1919-1923). E.Lejnieks organized Central Library of the LU and also the library of Faculty of Mathematics and Natural Sciences. E. Lejnieks also organized and ran the Congress of Researchers of Mathematics in 1923which can be considered the first congress of Latvian mathematicians. He participated in international congresses of mathematicians. E. Lejnieks lectured on more than 10 different subjects of mathematics. His teaching materials and lectures in Algebra and Number theory were published as books. E.Lejnieks was awarded an Order of the Three Stars in 1928. In 1934 he was elected an Honorary Doctor of the University of Latvia.