Reverse chromosome painting has become a powerful tool in clinical genetics for the characterization of cytogenetically unclassifiable aberrations. In this report, the application of a sensitive and rapid procedure for the complete and precise identification of four different de novo structural chromosome abnormalities is presented. These chromosome rearrangements include a marker derived from chromosome 3(cen-q11), an interstitial deletion of chromosome 13 [del(13)(q14q22)], an unbalanced translocation [46,XY, -4, +der(4)t(4;8)(p 15.2;p21.1)] leading to Wolf-Hirschhorn syndrome, and a partial inverted duplication in conjunction with a partial deletion of chromosome 5p [46,XX, -5, +der(5)(:p13-p15.1::p15.1-qter)] which is responsible for the manifestation of the cri-du-chat syndrome. The importance of a fast and reliable evaluation of complex chromosome aberrations in pre- and postnatal diagnosis with regard to comprehensive genetic counselling is emphasized.