The present study aims to examine the mathematical language use of primary prospective teachers through the mathematical texts they write. Forty-seven 3rd-year prospective teachers studying in the Department of Mathematics Education at a university participated in the study. The prospective teachers were asked to solve 4 open-ended mathematics problems, in which 3 of them were taken from the Programme for International Student Assessment (PISA) 2012. The data were analyzed through the content analysis method. The main findings of the study illustrate that the language used by the prospective teachers in the mathematical texts they have written were incomplete or incorrect in logical connective use, equal, congruent, approximate symbols, time measurement expressions, rational numbers, abbreviation, division algorithm, ratio-proportion representation and the presentation of solutions. The errors and ambiguity in participants' proportion.