Seven monoclonal antibodies(mAbs)were raised against Trypanosoma congolense procyclic form(PCF).Localization of the antigens recognized by the mAbs was determined in bloodstream form(BSF), PCF, epimastigote form(EMF)and metacyclic form(MCF)by confocal laser scanning microscopy(CLSM).Two mAbs(10F9 and 20H12)showed different fluorescent patterns among different life−cycle stages of the parasite.The 10F9 recognized a 76 kDa antigen of all life−cycle stages of the parasite and the antigen localization corresponded with that of a mitochondrion.While the 20H12 recognized 119 and 122 kDa antigens of all the life−cycle stages and the antigen localization corresponded with a flagellum in BSF and MCF, tip of a flagellum in PCF, and part of cytoplasm in EMF.Moreover, the 20H12 did not react to T.brucei gambiense, T.b.rhodesiense and T.evansi antigens in both CLSM and immunoblotting.Therefore, the antigens recognized by the 20H12 seem to be T.congolense specific.Although, further studies will be required for a full characterization of the T.congolense specific 119 and 122 kDa antigens, the mAb 20H12 and the specific antigens may be useful in not only establishment of T.congolense specific diagnosis methods but also studies on molecular mechanisms regulating differentiation of the parasite during life−cycle.