This experiment was attempted to investigate the inhibitory action of streptomycin. The organism used is Shigella flexneri 2a. The results are as follows: 1) Even under a level of 200γ/ml streptomycin, it cannot inhibit the oxidation of pyruvate, succinate, fumarate, malate, glutamate, and aspartate by whole cell suspensions. 2) When glutamate is added to a cell suspension that has previously been permitted to oxidize fumarate, an immediate increase in oxygen consumption is observed. This increase is scarcely prevented by streptomycin. 3) The oxidatin of a mixture of glucose, glutamate, and 10(-3)M Mg(++) by a cell suspension is prevented by streptomycin level of 200γ/ml. 4) Streoptomycin prevents especially aerobic growth of this organism in the synthetic medium and results in an increased accumulation of pyruvate as a metabolic product.