Dicyclomine hydrochloride is an antispasmodic agent. The MIC of dicyclomine against standard strains of Gram positive and Gram negative bacteria were performed by NCCLS broth dilution technique. These drugs showed a rapid killing action on Gram positive bacteria, Staphylococcus aureus NCTC 6571, 8530 and several other reference strains. The killing effect against Gram negative bacteria, Shigella boydii 8 NCTC 254/66 and Salmonella typhimurium NCTC 74 showed that the drug was bacteriostatic with respect to these strains. High rate of killing was achieved for most strains of Gram positive bacteria within 2 h. When administered to Swiss strain of white mice at doses of 30 and 60 microg/g of mouse, the drug could significantly protect the animals challenged with 50 MLD of Salmonella typhimurium NCTC 74. According to chi2 test, the in vivo data were highly significant (p<0.001). Since dicyclomine showed a remarkable inhibitory action against several pathogenic bacteria, in the course of time, it may be developed as a potent antimicrobial agent for many bacterial infections.