Henoch-Schönlein purpura (HSP) is an acute systemic vasculitis with unknown etiology, although several studies have found HSP to be related to cytokines such as tumor necrosis factor α, interleukin (IL)-1, and adhesion molecules. In the present study we determined the levels of cytokines such as IL-18 and endothelin-1 (ET-1) in children with HSP. Subjects were divided into three groups (group 1, 20 subjects with HSP; group 2, 10 subjects belonging to group 1 during their follow-up 4 to 6 months later; and group 3, 16 controls who were healthy siblings of the subjects). IL-18 and ET-1 levels were determined using enzyme immunoassay and expressed as mean ± standard deviation. We observed higher IL-18 levels in children with HSP (767.6 ± 145.1 pg/mL) than in controls (614.6 ± 66.54 pg/mL, p > 0.05), but IL-18 levels were found to be significantly lower in subjects with HSP in remission (502.7 ± 60.81 pg/mL) than in those who were in an active phase (1,050 ± 244.5 pg/mL, p < 0.05, n = 10). ET-1 levels were found to be significantly higher in subjects with HSP (1.93 ± 0.19 pg/mL) than in controls (1.10 ± 0.13 pg/mL, p < 0.05), although no significant difference was observed in ET-1 levels between subjects in group 1 (1.88 ± 0.30 pg/mL) and group 2 (1.91 ± 0.120, p > 0.05, n = 10). A positive correlation was observed between IL-18 and ET-1 levels in subjects with HSP (correlation coefficient [r] = 0.5254, p < 0.01). These results suggest that levels of IL-18 and ET-1 are worth monitoring during the clinical course of the disease, but caution must be exercised in extrapolating data based on small study samples.