对氨基苯甲酸（PABA）是苯甲酸的苯环上的对位（4-位）被氨基取代后形成的化合物。

纯品对氨基苯甲酸是白色针状单斜棱晶，露置于空气中或见光易氧化变黄，因此市售品常为淡棕黄色晶体。易溶于沸水，可溶于乙醇、乙醚、乙酸乙酯和冰醋酸，微溶于水及苯，不溶于石油醚。是两性物质，可溶于酸、碱溶液中。

4-Aminobenzoic acid (also known as para-aminobenzoic acid or PABA because the number 4 carbon in the benzene ring is also known as the para position) is an organic compound with the formula H₂NC₆H₄CO₂H. PABA, a white-grey crystalline substance, is only slightly soluble in water. It consists of a benzene ring substituted with an amino group and a carboxyl group.