The use of simple alkyl esters as skin permeation enhancers for indomethacin is described. The esters investigated were methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, and methyl valerate. Other solvents tested as enhancers were water, ethanol, diethyl succinate, ethyl acetoacetate, dimethyl sulfoxide, and Azone. The steady-state flux of indomethacin as measured in vitro through excised rat skin was enhanced about 1500-fold by ethyl acetate, methyl acetate, and methyl propionate relative to that from water. Relative to pure ethanol as permeation enhancing solvent, flux was enhanced over 20-fold using these three solvents. The other alkyl esters were about as effective as ethanol at increasing transdermal flux of indomethacin. Azone (5% in propylene glycol) increased the flux of indomethacin about 1100-fold relative to water and about 14-fold relative to ethanol. Dimethyl sulfoxide (30% in propylene glycol) and ethyl acetate (30% in propylene glycol) were relatively ineffective at increasing the flux of indomethacin. The use of ethyl acetate as a skin permeation enhancer in transdermal drug delivery is discussed.