Purpose Recent reports have found that sCD30 and sCD26 are correlated with some autoimmune diseases, especially in evaluating the activity of disease. However, little research has been done on the relation between sCD30 or sCD26 and primary immune thrombocytopenia（ITP） which is a kind of typical autoimmune disorders. Our study aimed to investigate the association between the levels of sCD30 or sCD26 and the activity of disease, and evaluate their value in ITP.Methods This study enrolled 47 patients diagnosed with ITP in Institute of Hematology and Blood Disease Hospital, Chinese Academy of Medical Sciences（Tianjin, China） from January 2015 to August 2015, including 23 patients with active ITP and 24 patients in remission. Twenty healthy persons were recruited as controls. Peripheral blood of all subjects was collected. The mRNA expression of CD30 was quantified by RT-PCR using SYBR Green as a double-strand DNA-specific binding dye on an ABI-7500 Sequence Detection System. Concentrations of sCD30 and sCD26 in the peripheral blood plasma were measured by ELISA. By analyzing patient characteristics, CD30 mRNA levels, sCD30 and sCD26 concentrations, we found the factor associated with ITP.RESULTS: The concentration of sCD30 was higher in active ITP patients（median, 35.82 ng/ml） than in patients in remission（median, 23.12 ng/ml; P=0.021） and healthy controls（median, 25.11 ng/ml; P=0.002）. Plasma sCD26 levels were decreased in patients in remission compared with controls（median, 599.4 ng/ml vs. 964.23 ng/ml; P=0.004）. No difference was found in sCD26 levels between active ITP patients and controls（P=0.072） as well as between patients in remission and active ITP patients（P=0.237）. Ratios of sCD26/sCD30 in active ITP patients were decreased compared with controls（P=0.005）, while no difference between ITP patients in remission and controls as well as active ITP patients（P=0.198, 0.093, respectively）. By analyzing the relevance of sCD30, sCD26 and sCD26/sCD30 ratio to platelet counts, disease courses and bleeding in active ITP patients, no other relation was found except concentrations of sCD30 were positively correlated with hemorrhage（r=0.493,P=0.017）.CONCLUSION: Levels of sCD30 and sCD26/sCD30 ratios may contribute to diagnose of ITP and evaluate the activity of disease while sCD26 could not.