Occupational bladder cancer due to aniline dye intermediates such as beta-naphthylamine and benzidine has long been known; benzidine congeners (o-tolidine and o-dianisidine) are highly suspect. Among 400 men from the Amalgamated Clothing and Textile Workers Union (ACTWU) Dyers locals in New York and New Jersey screened over a 4-year period, two cases of bladder cancer were detected. (Microscopic hematuria, not cytological evaluation, prompted further investigation.) Before a 1984 ACTWU screening program in North Carolina, three workers from the same plant self-reported bladder cancers. Another member, with inconclusive screening results, was diagnosed 2 years later. For these six cases, the mean age at detection was 56.5 years (age range, 38 to 79 years), a decade earlier than age at diagnosis of nonoccupational bladder cancer in men. The average latency from onset of exposure to diagnosis was 23.3 years. These cancers provide evidence to support the initiation of screening programs for high-risk workers. To overcome the emotional and economic disincentives faced by potential victims of occupational bladder cancer, training programs are needed. Worker involvement is required, through trade union representation where possible, to assure reliable training and the equitable distribution of screening and treatment costs.