AIM: To develop and characterize the monoclonal antibodies(McAbs) against Cryptosporidium parvum (C. parvum). METHODS: BALB/c mice were immunized with purified oocyst antigens of C. parvum from human isolates and McAbs against C. parvum were prepared by using hybridoma technique. The characterization of McAbs was studied by means of indirect immunofluorescent assay (IFA) and Western blot analysis. RESULTS: Four clones of hybridoma cell lines secreting McAbs against oocyst antigens of C. parvum were obtained. The immunoglobulin subclasses of these four McAbs were identified as IgM (Z4C8,Z3D7) and IgG1(Z2B6,Z3D2) and their light chains were kappa chain. IFA results showed that three McAb (Z4C8, Z3D7 and Z3D2) conjugates produced a diffuse fluorescence in the Cryptosporidium sporozoites (CSP) and one (Z2B6) produced local fluorescence in the oocyst wall of C. parvum. Four McAbs could recognize 4 of 42 polypeptide antigen bands of CSP with molecular weights of 20.5 kDa, 33 kDa, 60.5 kDa and 95 kDa, among which both Z4C8 and Z3D7 could recognize 20.5 kDa band that was defined as a principal antigenic protein of CSP. CONCLUSION: These four McAbs possess their own characteristics of recognizing antigenic epitopes on CSP, but react specifically against antigens of C. parvum.