A randomized clinical trial was performed in 160 children and 223 adults with acute immune thrombocytopenic purpura (ITP). The role of corticoids at this phase of the disease is still controversial. Therefore, patients were randomized to receive either conventional doses (1 mg/kg/day) of corticotherapy or low doses (0.25 mg/kg/day) for 3 weeks. The remission, defined by platelet count superior to 100,000/microliter was studied for adults and children after 6 months and 12 months, respectively. The statistical analysis showed no significant difference between the two corticotherapy regimens neither in children nor in adults. Overall, 74% of children and 41% of adults were in remission. For the first time in acute ITP, a randomized prospective trial showed that both in children and adults low dose corticotherapy (0.25 mg/kg/day) proves to have the same efficacy as conventional doses (1 mg/kg/day).