BACKGROUND Cystoscopy and histologic examination remain the standard methods for initial tumor diagnosis and monitoring for early detection of recurrences, since the sensitivity of conventional urinary cytology for the detection of urothelial tumors in urinary specimens is low. DNA image cytometry (ICM) and fluorescence in situ hybridization (FISH) have been suggested as ancillary tools. The goal of the current study was to compare the diagnostic value of DNA image cytometry and FISH for the noninvasive detection of urothelial tumors in voided urine. METHODS Cytospin preparations were prepared from voided urine collected prior to the resection of 26 noninvasive (pTa) and 11 invasive (pT1-2) tumors. Specimens from 14 patients with benign prostatic hyperplasia were used as negative controls. DNA ICM was performed using the AUTOCYTE trade mark cell analytical system on Feulgen-stained cytospin specimens. The commercially available UroVysion trade mark FISH multiprobe was used to analyze chromosomes 3, 7, and 17, and 9p21. RESULTS The overall sensitivity of cytology improved from 24% to 54% and to 78% if supplemented by ICM or FISH, respectively. Image cytometry detected all invasive tumors (pT1-2), while FISH missed one; FISH identified 19 of 26 (73%) pTa tumors, while only 9 (35%) of these tumors were aneuploid by ICM. The results of ICM and FISH were concordant in 37 of 51 (72%) cases. CONCLUSIONS The current study shows that both FISH and ICM can successfully be used as supplementary methods to detect the clinically most relevant group of invasive bladder carcinomas. However, UroVysion FISH is more sensitive in the detection of pTa tumors than ICM, as it recognizes individual chromosomal alterations that frequently prevail in urothelial tumors.