During a 25-years period (1970-1995), 10 children with congenital leukemia diagnosed according to the T.F. Necheles criteria (1979), were registered in Bulgaria. Seven of them were girls and 3 were boys. ANLL predominated in those cases (40%) in comparison with other age groups. In cases with ALL, the L2 subtype predominated. The clinical analysis showed marked hepatosplenomegaly in all cases, primary presentation of leukemic infiltrations in non-lymphatic organs (CNS - 40%, skin, kidneys) and extreme hyperleukocytosis (Leuk> 100.000/mm3) in 80%. Statistically important was the multiple risk factors expression in one and the same patient. One of the cases had Down's syndrome. Another child with congenital leukemia was born from a mother with Loewental syndrome. On the section material of the same child, a histologically proved polycystosis of the kidney's without leukemic infiltration was found together with the signs of an aggressive malignant disease. All patients rapidly deteriorated and eventually succumbed.