In the present trial, 101 patients with a clinical diagnosis of dandruff or seborrhoeic dermatitis with desquamation (dandruff) were treated with ketoconazole shampoo or hydrocortisone liniment in a double-blind (doubledummy) fashion. Significant reductions from baseline symptom severity (P<0.05) were seen in both treatment groups for desquamation, pruritis and erythema. There were no significant differences between the treatment groups at the endpoint. The proportion of patients who responded to the treatment, i.e. who were rated as normalized or markedly improved, was slightly higher in the ketoconazole group as judged by both investigator assessment (88% in ketoconazole vs. 80% in hydrocortisone group) and patient assessment (86% in ketoconazole vs. 82% in hydrocortisone group). Similarly, the percentage of normalized patients was higher in the ketoconazole group compared with the hydrocortisone group. The difference reached a statistically significant level (P= 0.011) in patient assessment. Seven of the 51 (13.7%) ketoconazole patients reported adverse events compared with 6 of the 50 (12%) hydrocortisone patients. All but one of the adverse events were dermatological or cosmetic in nature. It is obvious that the double-dummy design caused additional adverse events for ketoconazole patients, since the placebo liniment contained propylene glycol and isopropyl alcohol, which are known to cause skin irritation. Two ketoconazole patients discontinued the treatment due to irritation. Two hydrocortisone patients discontinued only the liniment treatment, one due to irritation and one due to itching. In conclusion, ketoconazole 2% shampoo is at least as effective as hydrocortisone 1% liniment in the treatment of dandruff. Ketoconazole shampoo may normalize the dandruff condition more often than hydrocortisone liniment does. Both treatments were well tolerated.