A dual-centre, randomized, double-blind, vehicle-controlled study was conducted to evaluate the safety and efficacy of short courses of therapy with imiquimod 5% cream in clearing >/=75% of baseline solar keratoses (SK) within a field of treatment. Subjects with 5-15 baseline SK within one treatment area (scalp, forehead and temples, or both cheeks) were randomized to apply imiquimod or vehicle cream to the entire treatment area three times a week for 3 weeks. Subjects were assessed 4 weeks after completing the first course for clearance of lesions. Subjects with <75% clearance were commenced on a second 3-week course of study cream. Subjects with >/=75% clearance were followed up until study completion without further therapy. All subjects were evaluated at the study endpoint of 14 weeks after initiating therapy for assessment of the primary outcome (>/=75% clearance of baseline solar keratoses). Twenty-one out of 29 (72%) imiquimod-treated subjects cleared >/=75% of baseline lesions compared with 3/10 (30%) subjects using the vehicle cream (Fisher's exact test, P = 0.027). Imiquimod was well tolerated. The present study has a short follow-up endpoint, but suggests that imiquimod is a potential therapeutic alternative in patients with SK.