Levels of an interleukin 10 (IL-10) are reduced in asthmatic patients in comparison to healthy subjects. Fact, that IL-10 is produced by Th1 and that inhibits cytokine production by Th2 lymphocytes has led to the concept that IL-10 might be beneficial in mitigating allergic inflammation. The purpose of this study was to define the effect of 4 week monotherapy with triamcinolone acetonide or nedocromil sodium on the serum level of IL-10, bronchial hyperresponsiveness and clinical parameters in atopic asthma children. It was an 8 week, randomised, double-blind trial of 37 children with moderate asthma allergic to house dust mite. Patients were randomly allocated to receive 200 mcg triamcinolone twice daily (n = 18), or 0.004 g nedocromil four times daily (n = 19). Thirty children completed the study. After treatment with triamcinolone the level of IL-10 in blood serum significantly increased, bronchial hyperreactivity significantly decreased, and all clinical parameters improved. Mean IL-10 levels in serum before and after treatment with triamcinolone were 7.5 pg/ml with 95%CI 6.79%-8.22% and 14.21 pg/ml with 95%CI 11.33%-17.09% respectively (p < 0.001). After treatment with nedocromil, clinical symptoms improved significantly, IL-10 serum levels and bronchial hyperreactivity did not change significantly (p = 0.094 and p = 0.09 respectively). This study demonstrates that one possible way by which triamcinolone contribute to inhibition of inflammation is by effect on IL-10.