Escherichia coli causes intestinal and extraintestinal infections and has been an indicator of fecal pollution in water and food. BALB/c mouse was immunized by injection of somatic E. coli (ATCC 8739) cells to produce monoclonal antibodies. Splenocytes of mouse were fused with myeloma cells (Sp2/0-Ag14). Two hybridomas secreting monoclonal antibodies were established after being cloned. In SDS-PAGE analysis of E. coli antigens 37 protein profiles appeared from 14 kDa to 182 kDa. Western blot analysis using polyclonal antibodies demonstrated that protein antigens of 41 kDa, 38.2 kDa and 31.7 kDa were immunodominant. Monoclonal antibodies DY-CM1 and DY-CM2 recognized 31.7 kDa and 2.0 kDa antigens in Western blot analysis, respectely.