Itraconazole is an orally active triazole antifungal which has been compared to griseofulvin in a number of double-blind trials. In dermatophytosis with a non-fixed treatment regimen for a maximum of 3 months, itraconazole 100 mg o.d. has produced a 100% mycological cure rate as compared with a 67% rate with griseofulvin 500 mg o.d. (p less than 0.01). Based on the pharmacokinetic profile, 100 mg itraconazole daily was then compared with 500 mg ultramicronized griseofulvin daily using a fixed treatment schedule of 15 days in tinea corporis and/or cruris and 30 days in tinea pedis and/or manus. In all studies in tinea corporis/cruris (n = 277), the superiority of itraconazole was shown for the clinical outcome at the last follow-up visit 2 weeks post-therapy (88 vs. 69%, p less than 0.01) and in the mycological outcome at the last follow-up visit (81 vs. 65%, p less than 0.05). In tinea pedis/manus (n = 210), the clinical response was virtually the same for the two treatment groups, but the most important finding was the mycological outcome with a significantly better result in favor of itraconazole at the end of treatment (77 vs. 61%, p less than 0.05) even more pronounced at the follow-up visit (85 vs. 48%, p less than 0.01). We conclude that itraconazole 100 mg daily in the treatment of tinea corporis/cruris and in tinea pedis/manus is significantly more effective than 500 mg griseofulvin daily when fixed treatment regimens are used. Furthermore, the best results are obtained with itraconazole 2-3 weeks after the end of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)