The presence of disseminated neuroblastoma cells in bone marrow in children over 1 year old is important for clinical staging and risk assessment at diagnosis and for therapy monitoring. Reliable detection of single tumor cells in bone marrow may be a factor of great prognostic significance. Currently disseminated NBL cells are detected by conventional cytomorphological examination of bone marrow smears but this method is not sensitive enough to detect single tumor cells. The development of more sensitive methods of evaluation bone marrow is needed. For this purpose Neuroblastoma Bone Marrow Committee developed standard immunocytochemical assay based on detection of the neuroblastoma-specific antigen. Disialoganglioside GD2 is a surface antigen expressed on neuroblastoma cells but not detectable on the surface of normal bone marrow cells. This article describes significance of immunoctochemical method of identification neuroblastoma cells in bone marrow.