The chromosomal region 11p15 harbours several imprinted genes, i.e. genes which are expressed in a parent-of-origin manner. Opposite molecular disturbances in 11p15 are associated with two distinct disorders associated with disturbed growth, Silver-Russell and Beckwith-Wiedemann syndrome. Due to the complexity of the 11p15 region and the interactions between the different genes, the interpretation of copy number variations in 11p15  is complicated. The clinical outcome of micro-duplications or –deletions is influenced by size, breakpoint positions and parental inheritance of the imbalance as well as by the imprinting status of the affected genes. Based on own cases and those from the literature we give an overview on the genotype-phenotype correlation in chromosomal rearrangements in 11p15 as the basis for a directed genetic counselling. (By Prof. Thomas Eggermann, http://jmg.bmj.com/content/early/2012/07/25/jmedgenet-2012-100967 )