Two identical randomized, multicenter, placebo-controlled studies were conducted to evaluate the efficacy and safety of imiquimod cream 2.5% (n = 159), imiquimod 3.75% (n = 160) or placebo (n = 159) in actinic keratoses (AK) of the face and balding scalp. Imiquimod or placebo cream (up to 250 mg x 2) were applied once daily for two 2-week treatment cycles, with a 2-week no-treatment interval between cycles. Efficacy was assessed at 8 weeks post-treatment. The primary efficacy endpoint was the complete clearance rate, defined as the percentage of patients with zero lesion count at the end of the study. Complete clearance rates were 6.3, 30.7 and 35.6% in the placebo, imiquimod ...