The present paper reported on an anti-CCA monoclonal antibody, McAb-IIID 10, which could be used in determinations of both parasite-oriented circulating antigens and specific anti-CCA antibodies. The established competitive ELISA (C-ELISA) using McAb-IIID 10 to detect schistosome-antibodies showed high sensitivity and specificity in the diagnosis of schistosomiasis with few cross-reactions. In field trials, coincident rates in 3 separate batches of serum samples when subjected to double-blind detections were obtained. A total of 1,915 serum samples had been determined by C-ELISA, among them 113 acute cases achieved a 100% positive rate, 765 chronic and 25 late cases showed 96.3% and 72% positive respectively. 70% of the 66 cured schistosomiasis cases turned to be negative. None of the 750 normal individuals showed positive reactions. No cross reaction was found in 27 sera from hydatidosis, whereas 1 and 2 positive reactions were found in 43 paragonimiasis sera and 126 clonorchiasis sera respectively. The established McAb-IIID 10 involved Dot-ELISA was found of value in the assessment of effective chemotherapy and showed a high negative conversion rate of 97.9% in 48 cured schistosomiasis patients. In 16 experimentally infected rabbits, 12 became negative in Dot-ELISA determinations at the 8th week post treatment, and the remaining 4 treated ones, the titer as well as the reaction intensity were also found reduced. A good coincidence rate was also found between C-ELISA and Dot-ELISA, their detection results may be complementary each other.