A population of 26 children of both sexes mean age 8.5 +/- 5.8 years with thrombocytopaenic purpura, disease duration at least 7 months (2.5 +/- 1.8 years), platelet count 22 000 +/- 12 000/mm(3) was studied. Patients were divided into three age groups; I: 2-6 years (8 children); II: 7-10 years (10 children); III: 11-16 years (8 patients). Careful history, physical examination, complete blood count with blood smear, platelet autoantibodies, bone marrow aspirate, and response to intravenous immunoglobulins (IV Igs) were evaluated. Statistical analysis was performed by chi(2) test. Platelet count, duration of disease, megakaryocytic reduction, need of splenectomy were significantly lower in younger children than older children of III group (P < 0.05). All patients were responsive to IV Ig. No significant differences of presence of platelet autoantibodies, were found among the groups. Relapse after splenectomy was observed in four older patients among whom three had Evans syndrome: complete remission was obtained with rituximab. Disease duration appears to be associated to megakaryocytic alterations and patient age.