For the purpose of preventing suppuration of wounds of the oral cavity and throat, we attempted to develop a viscous solution of dibekacin sulfate (DKB) as a suitable medication. Solutions of different viscosity and antibacterial potency were prepared by mixing DKB, sodium carboxymethyl cellulose (CMC-Na), and water in varying proportions. Studies were then performed to ascertain relationships between the concentration of CMC-Na pH and viscosity, and between the viscosity and diffusion of DKB. The concentration of CMC-Na giving rise to optimal clinical efficacy was determined, and the concentration of DKB necessary for clinical treatment was estimated on the basis of the ionic binding constant between DKB and CMC-Na. As a result, the optimum CMC-Na concentration was found to be 2%, while the optimum DKB concentration was estimated to be 100 micrograms/ml.