Аннотация:We analyzed CD95(Fas/APO-l) antigen expression on bone marrow blasts in 38 children with acute lymphoblastic leukemia (ALL) receiving a treatment in the Department of Leukaemias at the Cancer Research Center in 1987–1989 years (n = 22) and in 1994–1997 years (n = 16). CD95 antigen expression was studied by monoclonal antibodies (MoAbs) IPO-4 in indirect immunofluorescence analysis. CD95 antigen was expressed on 35.8±7.5% bone marrow blasts, most frequently (63.6%) in the clinically favourable Pre-B ALL. Only in this group CD95 antigen expression was correlated with CD10 antigen expression that has a positive influence to the time of complete remission in ALL patients. Our data showed that CD95 expression on blast cells is a favourable prognostic sign, associated with increased relapse-free and total survival. On the contrary, the absence of CD95 antigen on blasts is an unfavourable sign for disease evolution.