OBJECTIVE: To assess the diagnostic and prognostic performance of a noninvasive FGFR3 mutation analysis. After transurethral resection (TUR) of noninvasive bladder transitional cell carcinoma (B-TCC), recurrence occurs in 70% of patients, thus justifying cystoscopic surveillance. MATERIALS AND METHODS: A prospective multicenter study was carried out with a 2-year follow-up of patients with superficial B-TCC. Urine samples were collected before TUR and then before each cystoscopy during follow-up. Screening for the most prevalent FGFR3 mutations was done using urinary cells. The prognostic significance of an FGFR3 mutation at the time of the initial diagnosis was determined. The performance of the test in diagnosing and/or predicting recurrence during follow-up was assessed by calculating sensitivity and specificity. RESULTS: Of 191 patients studied, 74 (39%) had a positive analysis before TUR (FGFR3 mutation group). The presence of an FGFR3 mutation at the time of diagnosis was associated with a shorter time to recurrence (P = .02). During follow-up, 68 patients from the FGFR3 mutation group were evaluated. FGFR3 mutation analysis showed a sensitivity of 0.73 and a specificity of 0.87 when compared with the results of cystoscopy. A positive urine test was predictive of recurrence either at the time of the positive result or later during the 2-year follow-up, with a sensitivity of 0.70 and a specificity of 0.87. CONCLUSION: Among patients with an FGFR3 mutation in the initial tumor, a noninvasive urine test during follow-up can be valuable in diagnosing or predicting subsequent recurrence.