The change of the skin are acute reaction of erythema or sunburn, and/or prolonged and accumulated exposure commonly associated with degenerative changes, skin, aging, actinic keratosis and carcinoma after exposure to ultraviolet light. Topically applied protective agents are screen or barriers, absorb light of a particular wavelength or reflect it, which protect viable cells and has been used to decrease the risk of development, to prevent exacerbation of photodermatoses, pigmentary disorders, as melasma and freckles. The purpose of the study was to evaluate and comparative the several sunscreen agents available on the human skin of 40 healthy volunteers by indoor method and sunlight. The results were as follows: 1. In the development of minimal erythema doses, the average noted 4.8 minutes in ultraviolet light-B, 12.6 minutes in ultraviolet light-A, and 15.4 minutes in sunlight. 2. The sunprotective factors of 1.7% p-aminobenzoic acid, 0.3% benzophenone in cream were 12.1 in ultraviolet light-B, 8.2 in ultraviolet light-A, 6.3 in sunlight with highest effectiveness, and that of 5% p-amino-benzoic acid in oil were 1.6, 2.4, 1.3 with lowest effectiveness. 3. 1.7% p-aminobenzoic acid, 0.3% benzophenone in cream gave protection similar to that of 5% p-aminobenzoic acid in 70% ethylalcohol. 4. In the vehicle, the effectiveness of alcohol type agent is better than that of oil type of 5% p-aminobenzoic acid.