Dapsone, a synthetic sulfone that has been available for over 60 years, has been used to treat a myriad of cutaneous disorders. Prior to the general acceptance of isotretinoin, oral dapsone had been reported to be effective in the treatment of nodulocystic acne. However, the potential for systemic toxicity prevented its widespread adoption in the treatment of acne. For many years scientists explored the possibility of developing a topical formulation of dapsone for the treatment of acne in the hope of minimizing the adverse hematologic effects of oral dapsone. Such a formulation had been unavailable until recently. Dapsone 5% gel (Aczone) was recently developed to treat acne vulgaris. This topical formulation was approved in the US based on two randomized, vehicle-controlled studies. A 12-month, open-label study was also conducted to assess the safety and efficacy of topical dapsone over the long term. Finally, two open-label phase I pharmacokinetic studies were conducted to evaluate the systemic absorption of topical dapsone compared with oral dapsone. This article reports the results of these studies, which show a reduction in acne lesion count comparable to those observed in clinical trials of other approved topical acne therapies. With regard to safety, the studies demonstrated that the concentrations of dapsone and N-acetyl dapsone remain low and do not accumulate over time once steady state is reached. Of the total of 50 patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency in all the studies, only two experienced a drop in hemoglobin levels, and those shifts in values were consistent with fluctuations observed for other study participants. A recent study evaluating the risk of hemolysis in patients with G6PD deficiency found topical dapsone 5% gel to be safe to use in this patient population. Based on the observations noted in the above-mentioned studies, we conclude that topical dapsone 5% gel is safe and effective in the treatment of acne vulgaris.