Immune thrombocytopenia (ITP) is an autoimmune disease where platelets are destroyed prematurely. In the majority of children the disease resolves but in some it becomes chronic. To investigate whether the two forms of the disease are similar or separate entities we performed DNA microarray analysis of T-cells from newly diagnosed children and children with chronic ITP. We found complete separation of the expression files between the two forms of the disease. Furthermore, the gene expression of several cytokines differed between the two forms of the disease. This was also reflected in plasma with increased levels of IL-16 and TWEAK and lower levels of IL-4 in newly diagnosed compared with chronic ITP. Thus, our data indicate that the two forms of the disease may be separate entities.