592527 Disclosed is a process for the preparation of a the most stable crystalline polymorphic form of fluazinam (i.e. polymorphic Form I of 3-chloro-N-(3-chloro-5-trifluoromethyl-2-pyridyl)-?,?,?-trifluoro-2,6-dinitro-p-toluidine / 3-chloro-N-[3-chloro-2,6-dinitro-4-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2-pyridinamine) exhibiting an X-ray powder diffraction pattern having characteristic peaks expressed in degrees 2? (+/- 0.20 DEGREE ?) at about 8.7, 10, 12.0, 13.7, 14.5, 17.4, 18.5, 19.7, 21.8, 22.9, and 30.2 the process comprising the steps of crystallizing fluazinam from a solvent selected from ethanol, diethyl ether, acetone, isopropanol, toluene, acetonitrile, methylene chloride / dichloromethane and n-hexane and isolating the resulting crystals.