The sensitivity of a reagent strip test for the diagnosis of schistosomiasis by detecting circulating cathodic antigen (CCA) in urine was evaluated under field conditions using 251 stool and urine samples collected from a Schistosoma mansoni-endemic area of Ethiopia. The specificity of the test was evaluated in an area where schistosomiasis is not endemic. Stool samples were examined microscopically using duplicate Kato slides and formol-ether concentration methods. The effectiveness of the test in monitoring efficacy was also evaluated following chemotherapy. The results revealed that detection of CCA in urine using the one-step reagent strip test was superior to the stool examination methods (P<0.05) in indicating the prevalence of the disease. Assuming the combination of parasitological test results as the gold standard, the sensitivity and specificity of the test were 82.1% and 75.9%, respectively. The results of egg counts suggested the potential use of urine CCA in indicating the intensity of infection as an alternative to parasitological methods. The sensitivity and specificity of the test were 75% and 73.7%, respectively, following chemotherapy. Diagnosis of S. mansoni infection in urine using reagent strips would provide information on the prevalence of the disease, although further study is needed to improve its sensitivity and specificity.