Angiogenesis was estimated in childhood acute lymphoblastic leukemia (ALL) by the use of a novel morphometric method. This was compared with the widely used one of microvessel density (MVD). Bone marrow biopsies were evaluated by immunostaining with anti-Factor VIII related antigen (FVIIIRAg). Angiogenesis was calculated as volume corrected microvessel density index (VC-MVDI), taking into account the bone marrow cellularity. According to our results both MVD and VC-MVDI were increased at diagnosis of ALL in comparison with the control group. However the VC-MVDI increment was not statistically significant. Therefore, VC-MVDI could be more representative of the true increase of angiogenesis, correlating better with the outcome of the disease.