The existence of unfair terms is the major problem of contracts of adhesion, A preventive control system is in place in the Chilean Consumer Protection Law, and its practical application is the subject of analysis in this work. As a conclusion, the system is rendered as inefficient in protecting consumers, its presence being minimal in the relevant courts; in addition to this, there are several disperse rulings on the matter. In order to obtain the goal of protecting consumers, this work propounds a preventive control system by means of a commission of unfair terms of contract that would summon all the interested parties.El principal problema de los contratos por adhesión consiste en la presencia de cláusulas abusivas. En Chile existe un sistema de control previsto en la Ley de Protección a los Consumidores, cuya aplicación práctica se analiza en este trabajo. Se concluye que el sistema es ineficaz para proteger a los consumidores, siendo marginal su presencia en los tribunales competentes, a lo cual se suma un cúmulo de fallos disperso. Vara propender a una mejora en el objetivo de proteger a los consumidores se propone un control preventivo mediante una comisión de cláusulas abusivas que convoque a los distintos actores involucrados.