Abstract: The accessory cholera enterotoxin (Ace) is one of the identified toxin of Vibrio cholerae. The gene coding for Ace toxin was successfully cloned in Escherichia coli expression system, pBAD/Thio-TOPO vector. The Ace toxin causes a mild cholera manifestation, increases the potential differences across the intestinal epithelium and alters ion transport. All these characteristics are proposed as contributing factors in causing diarrhea in human. In this study, the Ace protein was expressed in the Escherichia coli (E. coli) host strain, LMG194. Several parameters and conditions including host strain, temperature of culturing, arabinose concentrations, antibiotic concentrations and a suitable time course induction were performed in order to get the expression of the Ace protein. Secreted toxin obtained from the supernatant produced a fusion-protein (combination of the Ace protein and HP-thioredoxin protein) with a molecular mass of 34 kDa (the Ace protein is expected to have a molecular weight of 18 kDa). The fusion protein was detected by anti V5-HRP epitope tagged antibody. However, the Ace protein failed to be expressed in another E. coli host strain, TOP10 cell, which could be due to the deleterious effect of the toxin to the cell.