Preliminary results of a bladder cancer screening program were presented. The program was started by the DuPont Chemical Company in 1954 and included 1,901 male workers, mostly white, at a chamber works facility. The subjects were enrolled in the program if it was likely that they would be exposed to beta-naphthylamine (91598) or benzidine (92875). Information was taken from medical records and urinalyses. A total of 316 bladder cancer cases were diagnosed, 300 among white workers. Of these, 142 cases had cytological evidence of malignant cells in the urine. Among the screened bladder cancer cases, the median number of hematurias was 6. The median number of hematurias was 4 in the non screened cases. The median number of hematurias in individuals without bladder cancer was 2. The number of individuals who developed bladder cancer after finding abnormal cells in the urine was 10 times those who had normal cytologies. The author notes that hematuria is regarded as the best clinical predictor of early bladder disease. The ultimate goal of the program is to stratify the study population as a function of intensity of exposure and to utilize all of the clinical signs to assess the extent of the disease.