The authors present the case of a vertically HIV infected, six-year-old girl, with precocious puberty. The late diagnosis of HIV both in the mother and in the child is of significance. Different causes of adrenarche precox are also discussed. In pediatric practice vertical HIV infection should be taken into consideration in differential diagnosis. In routine care of HIV-infected children, monitoring of development including sexual development is indicated. The presence of symptoms of adrenarche precox, as in noninfected children needs in depth diagnostic investigations. The role of HIV infection and of antiretrovirus treatment in the pathogenesis of adrenarche precox remains unclear and needs further investigation.