A randomized double-blind trial was conducted to assess the local effectiveness and safety of a troche form of clotrimazole in the treatment of oropharyngeal candidiasis in cancer patients. One half of the patients received one 10-mg troche and the other half received one 50-mg troche, five times a day for two weeks. Clinical cures were observed in 50 episodes, resulting in a cure rate of 96%. The median duration of oropharyngeal candidiasis after the start of therapy was three days in those treated with the 50-mg troche and four days in those who had received the 10-mg troche. Side effects were minimal, and only one patient experienced nausea and abdominal pain. Both the 10-mg and 50-mg troches appear to be efficacious and safe, but the 50-mg dose may be preferable because it is somewhat more effective without additional toxicity.