Dihydroxyacetone (DHA) is a popular ingredient in sunless tanner and lotions. We sought to measure the absorption spectrum of hu- man skin after application of DHA. A male in his 30's applied DHA to one underarm once daily for seven days. Re ectance spectropho- tometry was performed on the treated and untreated side. The area treated with DHA revealed increased absorption in the 400-700 nm range. Compared to normal skin, the absorption spectrum of human skin after application of DHA is altered from 400-700 nm. Care should be taking with using lasers in these wavelengths on skin treated with DHA. <em>J Drugs Dermatol. 2016;15(11):1459-1460.</em>.