Inflammatory lesion counts were statistically significantly reduced at 2 weeks in tretinoin-treated subjects (P=.0110), and reductions in total lesion counts also were noted. The reduction in total lesion counts reached statistical significance at week 4 (P=.0305); at week 12, mean total, inflammatory, and noninflammatory lesion counts were statistically significantly lower in the tretinoin treatment group versus vehicle group (P<.05), and mean percentage reductions in lesion counts were significantly greater in the subjects with noninflammatory lesions treated with tretinoin compared with vehicle (P<.05). Mean percentage reductions in total, inflammatory, and noninflammatory lesion counts were 35.5%, 38.2%, and 33.6%, respectively, at week 12 for the tretinoin treatment group compared with 20.9%, 19.2%, and 20.4%, respectively, for the vehicle group (all P<.05). All adverse events were of mild or moderate intensity with the exception of severe skin irritation in one tretinoin-treated subject. At week 12, there were no statistically significant differences between treatment groups for any measured tolerability parameter.