The aim of this study was to evaluate the safety and efficacy of oral terbinafine (500 and 1000 mg day(-1)) in the treatment of cutaneous or lymphocutaneous sporotrichosis. A culture for Sporothrix schenckii was required for inclusion into this multicentre, randomized, double-blind, parallel-group study. Patients received either 250 mg b.i.d. or 500 mg b.i.d. oral terbinafine for up to a maximum of 24 weeks and were assessed up to 24 weeks post-treatment. The main efficacy outcome measure was cure, defined as no lesion and absence of adenopathy at the end of follow-up. Adverse events (AEs), laboratory tests, vital signs and ophthalmological examinations were also assessed. Sixty-three patients (14-85 years of age) were treated with 500 mg day(-1) (n = 28) or 1000 mg day(-1) terbinafine (n = 35). The majority of patients were cured after 12-24 weeks of treatment, and the response was dose-dependent throughout the study and at the end of follow-up. The cure rate was significantly higher in patients treated with 1000 mg day(-1) terbinafine compared with those treated with 500 mg day(-1) terbinafine (87% vs. 52%, respectively; P = 0.004). There were no cases of relapse after 24 weeks of follow-up in the 1000 mg day(-1) terbinafine group, compared with six relapses in the terbinafine 500 mg day(-1) group. Terbinafine was well tolerated and the frequency of drug-related AEs was slightly higher in the 1000 mg treatment group. Both doses of terbinafine were well-tolerated and effective for the treatment of sporotrichosis. The 1000 mg day(-1) terbinafine dose was more efficacious than 500 mg day(-1) in the treatment of cutaneous or lymphocutaneous sporotrichosis.