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Voided-urine cytology as a screen for the early detection of urinary bladder cancer is analyzed to determine its potential in an asymptomatic population. Previous cost-effectiveness as sessments predict that screening will extend life-span at a cost-per-detected-case that is comparable to those of other cancer screening efforts. The focus here is on investigating screening from the perspective of the individual contemplating the screening decision. The analysis is based on a computerized model of bladder cancer which integrates a Markov representation of the induction and progression of the disease with algorithms representing diagnostic and therapeutic intervention strategies, intervention effectiveness, and cost. It is shown that the utilities, as well as the probabilities, of true-positive, false-positive, and false- negative screening outcomes are affected by the particular testing regimen employed and the age at which screening takes place. Screening at age 55 or age 65 was analyzed for individuals of normal risk. Analyses predict that the predisposition of cytology screening to identify the high-grade, aggressive form of the disease will result in gains in life expectancy of more than three years for the asymptomatic true-positive case. Results support the decision to screen, and by requiring a repeatedly positive test result, the probability of a false-positive outcome will not exceed that of a true-positive outcome at age 65. Except for the risk of a false-positive outcome, cytology screening compares favorably with what could theoretically be obtained if a 100% accurate screening test were available. Key words: cytology screening; decision analysis; disease modeling; bladder cancer. (Med Decis Making 8:110-119,1988)