Practical Guide "Leukemia in Children" ed., Mentkevich G.L., et al., considers general and particular issues of hematology in practical activities. Diagnostic methods (laboratory, chromosomal analysis), types of leukemias, their classification are covered. The concept of apaptosis, pathogenesis, prognosis of leukemias is described. There are presented versions of treating various types of blood pathological processes (radiation and chemotherapy, cell transplantation). its possible complications are indicated (infection, anemia, pain syndrome, hemorrhages, hypercalcemia, tumor lysis).