[Klinefelter syndrome in a boy with symptoms of precocious puberty].

Klinefelter syndrome is one of the most frequent sex chromosomal aberration. It is usually not recognized before puberty and many patients remain never diagnosed. Delayed puberty and hypergonadotropic hypogonadism are typical in this syndrome. Early diagnosis and therapy with androgens is important for patients. We present case of 8-year old boy with Klinefelter syndrome who was admitted to our department because of precocious puberty.