During the years 1979 to 1981 a population-based case-control study of bladder cancer including papillomas was performed in Greater Copenhagen. After exclusions some 388 patients (290 males; 98 females) and an age- and sex-matched group of 787 controls (592 males; 195 females) remained for analysis. Controls were selected at random from the general population of the study area. All persons were interviewed concerning use of artificial sweeteners in addition to their exposure to a number of other known or suspected risk factors for bladder cancer. Fifty-five male bladder cancer patients (19.4%) and 150 controls (25.7%) had at some time used artificial sweeteners regularly. Among females 27.1% of cases and 25.9% of controls regularly used sweeteners. In neither sex was the relative risk significantly increased in users compared with non-users of artificial sweeteners. The relative risk of 0.78 in the two sexes combined was not significantly different from 1.0 (95% C.I.: 0.58-1.05). There was no indication of a regular increase in risk with increasing daily consumption of table-top sweeteners nor was there any indication of an increase in risk with a duration of regular use of artificial sweeteners. Taking into account a possible latency period between first regular use and bladder cancer development did not change the finding of an absence of association between use of artificial sweeteners and the risk of bladder cancer. Neither saccharine nor cyclamate users had an increased risk of bladder cancer. This population-based case-control investigation provides further evidence that it is highly unlikely that the consumption of artificial sweeteners has contributed to current bladder cancer rates in man.