This paper is aimed to determine the relation between reading comprehension skill and TEOG success. In this research, a mixed research method, sequential explanatory mixed design, is utilized to examine the relation between reading comprehension skills and TEOG success of 8th grade students throughly. In explanatory sequential mixed design researches, the research primarily begins with collecting and analyzing quantitative data. After this first stage, qualitative data are collected and analyzed. In the second stage of the research, qualitative stage, the results of the first stage (quantitative) are followed. The sampling of the research is 586 (304 male, 282 female) 8th grade students in total receiving education in different schools of Sivas in 2015-2016 school year. It is concluded that students who read more and understand what they read achieve more success in TEOG. In the light of the results of this research, considering the fact that TEOG exam system makes reading comprehension skill much more prominent.