Our experience in the treatment of chronic mucocutaneous candidiasis with ketoconazole is reviewed. Of 21 patients, 15 have evidence of deficient cellular immunity and eight have endocrine abnormalities. Six patients had concurrent dermatophytosis or chromomycosis. All patients responded to treatment. Mucosal lesions improved in 6.7 +/- 0.5 days and cutaneous lesions responded to 22.7 +/- 5.1 days. The responses by infected nails were more variable (mean response time 92.4 +/- 14.4 days). Concurrent dermatophytoses did not prolong response times. Adverse effects were infrequent: one patient had drug-induced hepatitis and two patients became hypertensive. The relationship of hypertension to ketoconazole treatment is unclear. One patient was able to remain in remission after treatment was discontinued. Two patients had relapses while on treatment. Candida albicans isolated from these patients was highly resistant to ketoconazole in vitro. We conclude that ketoconazole is an effective and well-tolerated drug for the treatment of the infectious component of chronic mucocutaneous candidiasis.