The aim of this study is to examine prospective mathematics teachers' skills of interpreting algebraic formulae at the student level. In this context, 84 prospective teachers studying in the senior class of the elementary mathematics teaching program of a university in Turkey constituted the participants of the study. In this study, the qualitative research approach was adopted, and the case study method was used. The data of the study were collected using the interpretation test that was prepared by the researchers and composed of formulae. The data obtained from the study were analyzed using the content and descriptive analysis techniques. As a result of the study, it was observed that prospective teachers did not examine the logic of the formulae, did not think too much about from where the formulae were obtained, and could not interpret the formulae at the student level. In the light of these results, it is suggested to raise awareness of the reasons underlying formulae in prospective teachers by providing the environments that improve prospective teachers' interpretation and reasoning skills on the formulae used in major area courses given during undergraduate education because the fact that prospective teachers comprehend the logic of the given formulae will have an effect on the teaching they will perform.