In the study of the modos of glucose oxidation using Sh. flexneri 1 a, 2 a, or 3 a as the test bacteria, and glucose, gluconate, or ribose as the carbon source of the medium, the following results were obtained. 1. Every one of these bacteria cultured in the glucose medium can oxidize glucose well, but can not oxidize gluconate nor ribose. Those bacteria growing on the gluconate medium can oxidize glucose and gluconate well, but hardly ribose. The bacteria growing in the ribose medium can oxidize glucose and ribose well but not gluconate. 2. From the results obtained in the experiment using DNP as an inhibitory agent, it is assumed that glucose is mainly oxidized by way of the Embden-Meyerhof pathway by the bacteria grown on each of these culture media.