Abstract: The present invention relates to a novel process for producing 3-chloro-1-formyl-4-phenylpyrroles having the general formula [I] as a useful fungicidal agent in agriculture and horticulture which is manufactured from the starting material of 3-phenyl-2,2,4-trichlorobutanal having the general formula [IV] as set forth in the following reaction formulae:By means of obtaining a pyrroline derivative having the general formula [III] as the intermediate compound, its production operation is greatly simplified and its yield rate is raised in comparison with the conventional processes. ##STR1## where X denotes the same or different kinds of substituent(s) being chosen from the group consisting of halo, nitro, and trifluoromethyl and n denotes zero or an integer of 1 or 2.