We report two cases of acute interstitial nephritis associated with Yersinia pseudotuberculosis infection. The patients had fever, abdominal pain, vomiting and acute renal failure coinciding with elevated agglutination antibody titer for Y. pseudotuberculosis. Renal biopsy revealed interstitial nephritis in both patients. Although it is well known that yersiniosis sometimes affects glomeruli, this is the first report to demonstrate acute interstitial nephritis in patients with Y. pseudotuberculosis infection.