The antifungal efficacy and tolerability of 1% terbinafine cream vs. 1% bifonazole cream were assessed in a single blind randomized trial in patients with pityriasis versicolor. Terbinafine, a drug of the allylamines group, a new class of anti-mycotic agents, blocks sterol biosynthesis in the pathogen through inhibition of squalene epoxidase and consequent squalene accumulation, a primarily fungicidal process. Forty pityriasis versicolor patients, (18 M, 22 F; mean age 32.4 years; min. 16, max. 65), used 1% terbinafine cream or 1% bifonazole cream for a maximum of 4 weeks. All patients were followed-up weekly both clinically and mycologically. Clinical cures, defined as negativization of each clinical parameter, were recorded for 20 terbinafine patients (100%) and 19 bifonazole patients (95%), with routine microscopy and Wood's light tests both negative. By the 2nd week of treatment, 2 terbinafine patients were mycologically cured (10%). By the 3rd week, 14 terbinafine patients (70%) and 5 bifonazole patients (25%) were mycologically cured. The present controlled clinical trial consequently demonstrates that terbinafine is rapidly effective and well tolerated for treatment of pityriasis versicolor.