A Japanese girl aged 8 years who presented with a 2-month history of uveitis subsequently developed tubulointerstitial nephritis. A percutaneous renal biopsy revealed massive interstitial mononuclear cell infiltrates consisting of CD4-positive T cells. Despite administration of topical corticosteroids, the ocular symptoms persisted. Systemic corticosteroid therapy dramatically reduced the ocular symptoms and urinary beta2-microglobulin (beta 2MG) concentration. However, reducing the prednisolone dosage induced recurrence of uveitis associated with increased levels of urinary beta 2MG. The CD4-positive T cell infiltration persisted in the second renal biopsy performed 6 months after the first renal biopsy. These observations suggest that the interstitial cell infiltration persists for a relatively long time in a proportion of patients with tubulointerstitial nephritis and uveitis syndrome (TINU). Although the renal outcome of TINU has been reported to be favorable, prolonged interstitial cell infiltration may affect long-term renal outcome. Selected patients with TINU should be followed with close observation.