In a double-blind, parallel group study we compared fluconazole 150 mg once weekly with griseofulvin 500 mg once daily for 4-6 weeks in the treatment of tinea corporis or tinea cruris. Eighty-four of 114 patients (74%) (39% after 3 weeks) were clinically cured in the fluconazole group compared with 72 of 116 (62%) (39% after 3 weeks) in the griseofulvin group (P = 0.06). In the fluconazole group 78% were mycological cured compared with 80% in the griseofulvin group. In the fluconazole group nine patients (7.5%) had treatment related adverse events and in the griseofulvin group 15 patients (12.5%) had adverse events. Fluconazole 150 mg once weekly for 6 weeks is both clinically and mycologically effective in the treatment of tinea corporis and tinea cruris and few side-effects were reported.