Procedure for the preparation of a polymorphic form of the levorotatory or dextrogyr enantiomer of modafinil, characterized in that it produces an X-ray diffraction spectrum comprising lines of intensity in the distances of the network: 8.54, 4.27, 4.02, 3.98 (Å), said process comprising the following steps: i) dissolving one of the modafinil optical enantiomers in a solvent selected from methanol, ethanol, propanol, isopropanol, butanol, isobutanol, 2-methyl-2-pentanol, 1 , 2-propanediol, t-amyl alcohol, methyl acetate, n-propyl acetate, n-butyl acetate, n-butyl acetate, ethyl format, diethyl ether, tetrahydrofuran, dioxane, dibutyl ether, isopropyl ether, ether t-butylmethyl, tetrahydropyran, chloroform, 1,2-dichloroethane, dichloromethane, chlorobenzene, ortho-, meta- and para-xylene, a mixture of ortho-, meta- and / or para-xylene, methoxybenzene, nitrobenzene, trifluorotoluene, toluene , acetone, methyl ethyl ketone, methyl isobutyl ilcetone, 2- one, cyclopentanone, isobutylmethyl ketone, 2-pentanone, 3-pentanone, acetic acid, pyridine, acetonitrile, propionitrile, 4-methylmorpholine, N, N-dimethylacetamide, nitromethane, triethylamine, N-methylpyrrolidone, heptane , 4-trimethylpentane, cyclopentane, cyclohexane, dimethyl carbonate, water and alcohol / water mixtures； ii) crystallize the modafinil enantiomer； iii) recover the crystalline form of the modafinil enantiomer thus obtained.Procedimiento para la preparación de una forma polimórfica del enantiómero levorrotatorio o dextrógiro de modafinilo, caracterizado porque produce un espectro de difracción de rayos X que comprende líneas de intensidad en las distancias de la red: 8,54, 4,27, 4,02, 3,98 (Å), comprendiendo dicho proceso las siguientes etapas: i) disolver uno de los enantiómeros ópticos de modafinilo en un disolvente seleccionado entre metanol, etanol, propanol, isopropanol, butanol, isobutanol, 2-metilo-2-pentanol, 1,2-propanodiol, alcohol t-amílico, acetato de metilo, acetato de n-propilo, acetato
