BACKGROUND Silver-Russell syndrome (SRS) is a rare condition, affects one in 100,000 births. Turner syndrome (TS) is a chromosomal disorder, with an incidence of one in 2,500 females. Patient with SRS and mosaic 45, X/46,X,del(X) karyotypes can have a wide range of phenotypic manifestations. The aim of this article is to present a case report of a patient with an extremely rare and not reported so far genetically confirmed diagnose of Silver-Russell syndrome and Turner syndrome. METHODS The patient is a 9-years old girl who had a karyotype of 45,X on prenatal amniocytes. After delivery she was small for gestational age and her phenotype was quite consistent with Russell-Silver syndrome: characteristic dimorphic facial skeleton with a triangular face with prominent forehead, thin nose, hypotonia and hemihyperthrophy. The girl was admitted to hospital due to short stature and deep body weight deficiency. Skin fibroblast and DNA analysis showed mosaic karyotype 45,X[14]/46,X,del(X)(p21.2) and hypomethylation of a gene H19 located on chromosome 11p15. At present the patient is treated with growth hormone in our clinic with good therapeutic results. CONCLUSIONS The diagnosis of one genetic disorder does not rule out the possibility of a second genetic disease. Early diagnosis of coexistence of two different genetic syndromes, although very difficult, may help with quickly, appropriate therapy for patients and prevent them from developing serious complications.