Abstract The role of 11p15 disturbances in the aetiology of Silver-Russell syndrome (SRS) is well established: in addition to hypomethylation of the H19/IGF2 differentially methylated regions, five patients with a duplication of maternal 11p15 material have been described. We report on a boy with SRS carrying a maternally inherited duplication of chromosome 11p15. The patient showed the typical clinical picture of SRS including severe intrauterine and postnatal growth restriction, relative macrocephaly, a prominent forehead, a triangular face, down-turned corners of the mouth and fifth digit clinodactyly. Body asymmetry was not observed. By molecular genetic analyses, MLPA and microsatellite typing detected a duplication of chromosome 11p15 and cytogenetic analysis showed an unbalanced translocation t(11;15)(p15.5:p12). The size of the duplicated region is approximately 8.8 Mb as determined by SNP-array analysis. The healthy mother carried a balanced reciprocal chromosome translocation t(11;15). Thus, there is an increased risk for further children with SRS due to 11p15 duplication. Additionally, the family is at risk for offspring with an 11p15 deletion and Beckwith-Wiedemann syndrome whereby the phenotype will be influenced by haploinsufficiency of additional genes at 11p15 due to the deletion. The balanced aberrant karyotype was identified in several other family members, but interestingly there was no history of recurrent miscarriages, intrauterine fetal death, or multiple congenital anomaly syndromes in the family.