OBJECTIVE: To research the curative effect of Chinese herbs for clearing away heat, promoting diuresis, nourishing the kidney, and consolidating essence in children with Henoch-Schonlein purpura nephritis (HSPN) with internal accumulation of damp-toxin using randomized controlled observations on large samples. To seek the mechanism of the therapy and its scope of indications. METHODS: Overall, 186 children with HSPN were randomly divided into two groups: treatment group (n=126) treated with Chinese herbs for clearing heat and promoting diuresis and a control group (n=60) treated with Western Medicine. The treatment was carried out for three courses of 4 weeks each. We recorded changes in patient urine routines, 24 h urinary protein, blood-coagulating series, immunoglobulin and T-cell subgroups, and improvements in main symptoms. We evaluated the alleviation of clinical symptoms and the improvement of proteinuria, hematuria, and other laboratory test results. Finally, we analyzed the patient population suitable for this therapy according to the relationship between the grouping of patient body weight and curative effect. RESULTS: Damp-heat syndrome improved in the treatment group, with a significant difference in total effective rate after a 4-week treatment (chi(2)= 13.5220, P=0.0002) and in curative rate after a 12-week treatment (chi(2)=6.3410, P=0.0118), compared to those in the control group. The curative effect in the treatment group was greater than that in the control group but there was no statistical difference between the two groups. The curative effect after a 4-week treatment of patients in the treatment group weighing 30 kg or less based on Traditional Chinese Medicine (TCM) signs and urinary protein was significantly greater than that in the control group. However, there was no statistical difference in the curative effect on urinary red cells and various indexes after a 12-week treatment between the two groups. CONCLUSION: Therapy for clearing away heat, promoting diuresis, nourishing the kidney, and consolidating essence using TCM is effective in children with HSPN from internal accumulation of damp-toxin. The therapy is especially suitable for patients weighing 30 kg or less. The curative effect may be related to the improvement of immune function and blood-coagulation. (C) 2014 JTCM. All rights reserved.