对氨基苯胂酸，俗称对阿散酸、阿散酸（Arsanilic acid），一种有机砷化合物，是苯胂酸苯环4-位被氨基取代形成的化合物。

无色或白色针状晶体。几乎无臭。有毒。不溶于稀无机酸、丙酮、乙醚、氯仿、苯，微溶于冷水、乙醇、乙酸，溶于热水、碳酸碱溶液、浓无机酸溶液、戊醇。 主要以两性离子形式（）存在。

Arsanilic acid, also known as aminophenyl arsenic acid or aminophenyl arsonic acid, is an organoarsenic compound, an amino derivative of phenylarsonic acid whose amine group is in the 4-position. A crystalline powder introduced medically in the late 19th century as Atoxyl, its sodium salt was used by injection in the early 20th century as the first organic arsenical drug, but was soon found prohibitively toxic for human use.