PURPOSE: To analyze clinical features of the tubulointerstitial nephritis and uveitis (TINU) syndrome in Japan, especially exacerbations or recurrences of uveitis. DESIGN: Retrospective observational study. METHODS: We reviewed the clinical features in 12 patients with TINU syndrome diagnosed by renal biopsy, who were evaluated and treated at the Department of Ophthalmology, Hokkaido University Hospital. Visual acuity was measured using decimal visual acuity. RESULTS: Patient age ranged from 10 to 33 years (mean 21 years), and females accounted for 83% of the cases. Both eyes were affected in 11 patients (92% ). All 12 patients initially experienced ocular symptoms, with hyperemia being the chief complaint. We diagnosed patients as having uveitis and conducted blood tests and urinalysis. Urinalysis did show characteristic findings, most notably glucosuria, increased β 2 microglobulin that were <10 times that of normal levels, and increased N-acetylglucosaminidose levels in a high percentage of patients. Recurrent or exacerbating uveitis was seen in six patients (50% ). In exacerbated or recurrent uveitis, in flammation was more severe (< 3+ cells of the anterior eye segment). The ocular inflammation generally responded well to treatment with oral corticosteroids, and the number of recurrences was lower at corticosteroid doses of < prednisolone 40 mg. CONCLUSIONS: Ophthalmologists play an important role in the initial discovery of patients with TINU syndrome. Because inflammation was more severe in exacerbated or recurrent uveitis, in instances where uveitis is refractory to local therapy, oral corticosteroids should be considered as early as possible. PURPOSE: To analyze clinical features of the tubulointerstitial nephritis and uveitis (TINU) syndrome in Japan, especially exacerbations or recurrences of uveitis. METHODS: We reviewed the clinical features in 12 patients with TINU syndrome diagnosed by renal biopsy, who were evaluated and treated at the Department of Ophthalmology, Hokkaido University Hospital. Visual acuity was measured using decimal visual acuity. RESULTS: Patient age ranged from 10 to 33 years (mean 21 years), and females accounted for 83% of the cases. Both eyes were affected in 11 patients (92%). All 12 patients initially experienced ocular symptoms, with hyperemia being the chief complaint. We diagnosed patients as having uveitis and conducted blood tests and urinalysis. Urinalysis did show characteristic findings, most notably glucosuria, increased β 2 microglobulin that were <10 times that of normal levels, and increased N-acetylglucosaminidose levels in a high perc In exacerbated or recurrent uveitis, in flammation was more severe (<3+ cells of the anterior eye segment). The ocular inflammation generally well well to treatment with oral corticosteroids, and the number of recurrences was lower at corticosteroid doses of