To determine the predictive value of flow cytometric deoxyribonucleic acid (DNA) ploidy and urine cytology in patients with superficial transitional cell carcinoma of the bladder, a retrospective analysis was performed on 181 patients who presented for evaluation of presumed superficial transitional cell carcinoma of the bladder. Of the patients 91 were confirmed to have superficial transitional cell carcinoma and were systematically followed with cystoscopy, flow cytometry and urine cytology from 1984 until 1989. They underwent 637 evaluations (mean 7 evaluations per patient). At initial evaluation, flow cytometry had 81% sensitivity and 57% specificity, while urine cytology was 75% sensitive and 94% specific. During the followup flow cytometry was 76% sensitive and 36% specific. Urine cytology was less sensitive (40%) but more specific (81%) than flow cytometry in followup evaluation. These results were similar whether intravesical chemotherapy or bacillus Calmette-Guerin was administered. To ascertain whether false positive flow cytometry represented early detection of recurrent transitional cell carcinoma not apparent at cystoscopy, patients with positive flow cytometry and urine cytology were followed longitudinally. False positive flow cytometry and urine cytology were equally predictive of recurrent transitional cell carcinoma progressively with time. However, for any given examination flow cytometry was more likely to detect and predict recurrent transitional cell carcinoma. At 4 years the bladder transitional cell carcinoma incidence for false positive flow cytometry and urine cytology was 87% and 84%, respectively.