The main objective of this article is to acquire in-depth knowledge of the training primary education teachers receive regarding transgender identities, as well as the resulting consequences in school realities. A phenomenological qualitative research approach was used to accomplish this purpose. The data were collected using a semi-structured interview technique. The participants were 38 primary education teachers from different public schools in the province of Cádiz, Spain. They acted as key informants, allowing us to gain knowledge, understanding, and meaning regarding our object of study. Among the results obtained, the absence of transgender identities in pre-service and in-service teacher training is observed. As a result, a severe lack of knowledge and confusion about the subject, as well as discriminatory values, are perceived in teachers. The need for transgender identities to be present in initial and continuous teacher training is stressed in order to see to the social and educational needs of transgender students in primary education and avoid reproducing the invisibility of transgender identities and the transmission of inegalitarian values.