The efficacy and tolerability of tazarotene 0.1% gel and adapalene 0.1% gel were compared in a multicenter, double-blind, randomized, parallel-group study in 145 patients with mild-to-moderate facial acne vulgaris. Both treatments were applied once daily in the evenings for up to 12 weeks. Compared with adapalene, treatment with tazarotene was associated with a significantly greater incidence of treatment success (> or = 50% global improvement) (78% vs 52%; P=.002) and significantly greater reductions in overall disease severity (P<.0001), noninflammatory lesion count (P<.0001), and inflammatory lesion count (P=.0002). In the early weeks of treatment, tazarotene was associated with transiently greater levels of burning, pruritus, erythema, and peeling compared with adapalene (P<.01). However, mean levels of these parameters were consistently less than mild in both treatment groups and, at the end of treatment, patients considered both treatments to be comparably well tolerated (the proportion of patients in each group who rated the comfort of their treated skin as comfortable or very comfortable was 76% with tazarotene and 69% with adapalene). Mean usage of study medication was 0.32 g per application of tazarotene and 0.42 g per application of adapalene, which resulted in cost-effectiveness ratios of $79.95 per treatment success for tazarotene and $107.88 per treatment success for adapalene. Sensitivity analyses suggest that these cost-effectiveness results are robust across a range of cost and efficacy assumptions. In conclusion, tazarotene 0.1% gel was more effective than adapalene 0.1% gel and was also a more cost-effective treatment option.