Henoch-Schonlein purpura (HSP) is a small-sized vasculitis affecting mainly children. Based on the hypothesis that an inherited predilection to hypercoagulability may predispose to HSP or may mark those who develop acute clinical manifestations, we evaluated the possible roles of methylenetetrahydrofolate reductase (MTHFR) gene C677T, factor V (FV) gene G1691A (Leiden), and prothrombin gene G20210A polymorphisms in patients with HSP. Fifty-two HSP patients (32 boys and 20 girls) from different ethnic groups (22 Jews and 30 Arabs) and 104 ethnically matched controls were studied for these three polymorphisms. The frequencies of these mutations for each group, separately and in combinations, are described. The mutation frequencies in the MTHFR, prothrombin and FV genes in HSP patients did not differ from those in controls. In a small number of individuals (n=5) homozygosity for the 677T thermolabile variant of MTHFR was associated with hematuria. To summarise, hypercoagulability does not seem to play a role in HSP. Studies in larger cohorts and possibly inclusion of additional factors may be needed to ascertain whether homozygoty for MTHFR 677T polymorphism can influence disease severity.