... New insights into cytogenetics from simultaneous painting of all pairs of chromosomes . Multicolor in situ hybridization (m-FISH) and Spectral Karyotyping (SKY) are molecular cytogenetic techniques that permit the simultaneous visualization of all human (or mouse) chromosomes in different colours (chromosome painting), facilitating a detailed karyotype analysis. ... In the present talk new insights into the induction of aberrations by high + low LET radiation, analysed by m-FISH will be discussed. ...