The objective of this paper is to assess the possible role of nitric oxide (NO) and leptin in Henoch-Schonlein purpura (HSP). We investigated the serum leptin and total nitrite levels in 22 children with HSP in the acute phase and after remission and in 20 age- and sex-matched healthy control. Serum leptin levels (nanograms per milliliter; median, min-max) were statistically higher in the acute phase (12.9, 9.1-19.5) than those in the remission phase (6.1, 3.7-10.5, p < 0.001) and in the control group (4.9, 3.8-7.5, p < 0.001). Also, serum nitrite levels (micromole per liter; median, min-max) were higher in children in the acute phase (45.0, 32.0-60.0) compared to those in remission phase (30.5, 23.0-48.0) and in the control group (29.5, 18.0-38.0) (p < 0.001, p < 0.001, respectively). There was a positive correlation between serum leptin and total nitrite levels (r=0.65, p < 0.001). We have demonstrated that serum leptin and NO levels were increased during the acute phase in children with HSP, and returned to normal levels in remission. We suggest that leptin and NO may have a role in the immunoinflammatory process of HSP, especially in the acute phase. Further studies are needed to clearly establish the roles of leptin and NO in the pathogenesis of HSP.