About one million Roma children "remain invisible" in South-East Europe, without documents or adequate healthcare, a Unicef report says.
Many Roma children in Serbia live in poverty
The report by the UN body for the protection of children found that in the region Romas (Gypsies) face exclusion and discrimination.
It also found that some 50,000 Roma children live as refugees in Germany.
Unicef urges the European Union to help improve the condition of Roma children, many of whom live in dire poverty.
The study found that in Romania and Bulgaria - new EU member states - up to one-third of Roma children were not in school, a proportion which reaches 80% in Bosnia-Hercegovina.
Unicef warned that when these children become adults, they will not be able to vote, make use of social services or register their own children.