Method of preparing an aqueous suspension containing fenofibrate and / or suspended phenofibric acid, a cellulosic derivative as a solubilization adjuvant and a surfactant, characterized in that the fenofibrate and / or the fenofibric acid are in crystalline form, respectively presenting a point of fusion in DSC from 79ºC to 82ºC or from 179ºC to 183ºC, and because the average particle size of fenofibrate or fenofibric acid (D (50)) is less than 250 nm, preferably 180 nm, characterized in that it has following steps: (a) mixing a part of the proportion of the cellulosic derivative in the final suspension, the surfactant and optionally the phospholipid with water under stirring until complete dissolution； (b) add fenofibrate and / or fenofibric acid to the mixture obtained in the previous stage with stirring until complete dissolution, then； (c) grind the mixture obtained in the previous stage in the presence of spheres, preferably spheres of polymer or zirconium oxide and / or yttrium, to a power sufficient to achieve a medium grain size of fenofibrate (D (50)) lower than 250 nm； (d) optionally homogenize the ground suspension obtained in the previous stage； (e) adjust the amount of cellulosic derivative and optionally water, and characterized in that the cellulosic derivative is hydroxypropyl methylcellulose.Procedimiento de preparación de una suspensión acuosa que contiene fenofibrato y/o ácido fenofíbrico en suspensión, un derivado celulósico como adyuvante de solubilización y un tensioactivo, caracterizado por que el fenofibrato y/o el ácido fenofíbrico se encuentran en forma cristalina, presentando respectivamente un punto de fusión en DSC de 79ºC a 82ºC o de 179ºC a 183ºC, y por que el tamaño medio de las partículas de fenofibrato o de ácido fenofíbrico (D(50)) es inferior a 250 nm, preferentemente 180 nm, caracterizado por que presenta las etapas siguientes: (a) mezclar una parte de la proporción del derivado celulósico en la suspensión final, el tensioactivo
