Wolf–Hirschhorn syndrome is a complex development disorder containing facial dysmorphy, development retardation, growth impairment, muscular hypotonia and occurrence of paroxysmal disorders. Characteristic dysmorphic features are hypertelorism, oblique eyelids, prominent high forehead, wide nose, short philtrum, micrognathia, low set dysplastic ears and gothic palate, in some cases cleft palate. Those features are described as “Greek warrior helmet”. Dysmorphia can be accompanied by various congenital defects, such as growth impairment, heart defects, coloboma, urogenital and skeletal abnormalities, deafness, and in 20% of patients kidney defects, which could lead in some cases to end of stage renal disease. Observed disorders are resulting from deletion of short arm of 4th chromosome and their severity, clinical outcome and intensity of development retardation depend on deletion size. In our article we present a boy with severe case of Wolf–Hirschhorn syndrome accompanied by renal dysplasia of his only kidney, which lead to end of stage renal disease during his infancy. He has been treated with peritoneal dialysis since then. In our patient’s case variety of congenital defects and severe development retardation cause bad clinical outcome and serious prognosis. Patient like that requires multidisciplinary medical care. Decision about initiation of renal replacement therapy in such a patient is still an important ethical dilemma.