This article reviews the anticipatory control mechanisms of the environ-mental impact assessment established in our legal system, especially analyzing the admissi-bility test of the projects submitted to the Environmental Impact Assessment System (EIAS). After an identification of the latest projects entered into the EIAS for a year and a half, and those not admitted in the same period, certain differences in criteria and causes for non-admission are identified among the environmental authorities of the different regions of the country when making this determination, which we analyze in great detail, with the aim of proposing certain considerations in the framework of the imminent modification to the SEIA, which are especially related to the need for coordination and coherence of the system, whose absence marks the development of this work. In summary, this paper at-tempts to emphasize the urgent need to systematically, permanently and flexibly regulate the environmental assessment procedure, from the earliest stages of the projects.El presente artículo revisa los mecanismos de control anticipado del proceso de evaluación ambiental establecido en nuestro ordenamiento, en especial analizando el examen de admisibilidad de los proyectos sometidos al Sistema de Evaluación de Impacto Ambiental (SEIA). Luego de un levantamiento de información de los últimos proyectos ingresados al SEIA, y de aquellos no admitidos a tramitación, se identifican ciertas diferencias de criterios entre las autoridades ambientales de las distintas regiones del país al tomar esta determinación, las que analizamos en detalle, con el objeto de proponer ciertas consideraciones en el marco de la inminente modificación al SEIA.