This article presents the results of the study made in the years 2015 and 2016 about the reliability of the Reading and Writing in Spanish (LEE by its initials in Spanish), Argentinian- Spanish battery test for analyzing its applicability on Costa Rican students. Its perspective is instrumental with quantitative methodology, where the calculation of reliability and the internal consistency of the test were determined with the Cronbach's Alpha statistic. The instrument was applied on a sample of 285 students of the educative region of Cartago, area where the content validity of the same test was carried out in a study conducted between 2013 and 2014 (Carpio and Méndez, 2016). The global results show that this battery test is composed by seven sub-tests, they can only be used with some modifications, the Word-reading sub-tests, pseudo-word reading, word-writing and pseudo-word writing. For this reason, it is recommended to elaborate a specific test for Costa Rica.