En las evaluaciones internacionales en lectura para Educación Primaria en Uruguay evidencian resultados preocupantes, 50% de niños tienen dificultades en lectura y escritura (INEEd, 2015). Desde la Facultad de Psicología de la Universidad Católica del Uruguay, se vienen trabajando sobre los procesos lectores: prueba de eficacia lectora TECLE (Cuadro et al., 2009), Eficacia ortográfica TEO (Cuadro et al., 2014), Dictado de palabras (Cuadro et al., 2014), estudio sobre léxico ortográfico y habilidad lectora en jóvenes lectores (Cuadro & Costa, 2015), diferencias procedimentales en el cálculo de la prevalencia del retraso lector en escolares hispanoparlantes (Cuadro et al., 2017). El objetivo es determinar la capacidad discriminativa de estas pruebas y reportar la prevalencia del déficit lector. Se evaluó 328 alumnos de 2° a 6° año de primaria de instituciones privadas de Montevideo. Se les administró:TECLE (Cuadro et al., 2009), TEO (Cuadro et al., 2014), TEO_P (Cuadro & Palombo, en prensa) y Dictado (Cuetos et al., 2007). Se corrieron estudios psicométricos, cálculo de capacidad discriminativa (sensibilidad y especificidad) utilizando Curvas Roc. El estándar de oro se construyo con la prueba de Lectura de palabras y pseudopalabras (Defior et al., 2006). Se muestran los principales resultados de la prevalencia del retraso lector. Palabras clave Psicometría, Curvas, Trastorno de la lectura, Niños ABSTRACT PRELIMINARY RESULTS:“EPIDEMIOLOGICAL STUDY OF DEFICIT READER IN EDUCATION PRIMARY IN MONTEVIDEO” Results from international assessments show that 50% of uruguayan primary school students have difficulties in reading and writing. (INEEd, 2015). The Faculty of Psychology of Uruguay´s Catholic University has been conducting research regarding the development of the reading process: a reading efficiency test (TECLE) (Cuadro et al., 2009), an orthographic decision efficiency test (TEO) (Cuadro et al., 2014), a word dictation test (Cuadro et al., 2014), studies regarding ortograhic lexicon and reading ability in young readers (Cuadro & Costa, 2015) and procedural differences in the determination of reading delay prevalence in Spanish-speaking students (Cuadro et al., 2017). The aim of this study is to determine the discriminative capacity of these tests and report the prevalence of reading deficits. A sample of 328 students from 2nd to 6th grades from private schools in Montevideo was used. Students were assessed with four instruments: TECLE (Cuadro et al., 2009), TEO (Cuadro et al., 2014), TEO_P (Cuadro & Palombo, in press) and word dictation (Defior et al, 2006). Psychometric tests were employed, the discriminative capacity (sensitivity and specificity) was assessed through the use of Roc Curves. The golden standard was constructed by using words and pseudowords decoding tests (Cuestos et al., 2014). The main results regarding the prevalence of reading deficits are shown. Key words Psychometrics, curves, Reading disability, Children