A process for preparing perylene pigments of the general formula (Ia) or (Ib) or mixtures thereof, by reacting perylenetetracarboxylic acids or functional derivatives thereof with aromatic diamines, where R1, R2 may be the same or different and may each independently be phenylene, naphthylene or pyridylene, where R1, R2 may each be mono- or polysubstituted by C1-C22-alkyl, C3-C22-alkenyl, C1-C22-alkoxy, hydroxyl and/or halogen, X1, X2, X3, X4, X5, X6, X7, X8 may be the same or different and may each independently be hydrogen or halogen, wherein the reaction is performed in the presence of a secondary or tertiary amine in an aqueous reaction medium.