Background: Urinary oxalate may contribute far more than urinary calcium to the pathogenesis of urinary calculi. Urinary oxalate may be reduced by restricting the intake of foods high in oxalate. The oxalate content of foods might be reduced by oxalate‐degrading bacteria. The purpose of this experiment was to reduce the oxalate content of foods with an oxalate‐degrading bacterium which was isolated from the feces of a Japanese male.Methods: An artificial intestinal juice was prepared by modifying Rogosa medium. An infusion of black tea was prepared from a commercial tea bag. The oxalate‐degrading bacteria used wereEubacterium lentumWYH‐1 which we have isolated. To 5 mL of the above oxalate‐containing artificial intestinal juice and infusion of black tea, 0.5 mL of the bacterial culture was added and incubated anaerobically at 37°C. Oxalic acid in the supernatant of the culture medium was assayed by high‐performance liquid chromatography.Results: In 24 hours, 1 × 106cells/mL ofEubacterium lentumWYH‐1 decomposed 100% of 1 mg/mL oxalate in the artificial intestinal juice. The oxalate in the black tea infusion (1 mg/mL) was also decomposed completely within 48 hours by 1 × 107cells/mL of the bacteria.Conclusion:Eubacterium lentumWYH‐1 was able to efficiently decompose th