The diagnosis of transitional cell carcinoma (TCC) in bladder washes is a diagnostic challenge to cytology. This study assessed the role of flow cytometry (FCM), image analysis (IA), and interphase cytogenetics by fluorescence in situ hybridization (FISH) as adjuncts in the cytodiagnosis of TCC in bladder washes. Forty separate samples of bladder washes were prospectively evaluated by conventional cytology (CY), FCM, IA, and FISH, and the results were compared with the subsequent surgical biopsy specimens which revealed 26 TCC (3 GR I, 6 GR II, 17 GR III) and 14 benign lesions. Using histology as the "gold standard" and following the previously published criteria for detection of TCC by CY, FCM, IA, and FISH, the concordance rates between histology and CY, FCM, IA, and FISH were 75, 74, 89, and 83%, respectively. CY, FCM, IA, FISH, and histology were concordant in 54% of the cases. The sensitivity of CY, FCM, IA, and FISH were 61, 72, 91, and 73%, respectively, while the specificity were 100, 80, 83, and 100%, respectively. The combined sensitivity of all the parameters was 96%. Interestingly, the false positive cases by FCM and IA showed cystitis. We conclude that IA has the highest sensitivity in detecting TCC in bladder washes followed by FISH, FCM, and CY, while CY and FISH have the highest specificity. This study indicates that FCM, IA, and FISH are useful adjuncts to cytology in the diagnosis of TCC in bladder washes. The finding of DNA-aneuploidy in cystitis warrants further investigation.