The present invention relates to a process for the preparation of diketopyrrolopyrroles of the formula (I), wherein A1, A2, A3 and A4 are as defined in the description of the present invention, to new diketopyrrolopyrroles of the general formula I obtainable by the process, and the use of the new diketopyrrolopyrroles of the general formula I for the preparation of inks, colorants, pigmented plastics for coatings, non-impact-printing material, color filters, cosmetics, polymeric ink particles, toners, dye lasers and electroluminescent devices, or as fluorescent markers for immunoassays and fluorescent tracers for leak detection of fluids. Furthermore the present invention relates to diketopyrrolopyrrole analogues of the general formula (II), wherein A1, A2 and A3 are defined in the description of the present invention, which are intermediates in the process for the preparation of diketopyrrolopyrroles of the formula I and can be used as crystal growth regulators ##STR00001##