Immigration from developing countries to Europe has greatly increased during the last few years. Very little information is available on children who immigrated with their biological family, thus this paper deals only with children immigrating by adoption. In recent years some studies have shown an increased incidence of precocious puberty among adopted children, but information on this issue is scanty. Several hypotheses have been put forward to explain precocious puberty in adopted children, including nutritional, ethnic and/or emotional factors. Untreated precocious puberty is associated with short stature and has social and psychological consequences in addition to those related to adoption. Therefore, indications for therapy need to be carefully planned. In adopted children age estimation is a possible source of error in timing of puberty as date of birth is often missing or inaccurate. Thus each child must be carefully evaluated.