Of 57 diverse organic acids screened for antiinflammatory activity in vitro 42 gave results equivalent to or greater than acetylsalicylic acid in the trinitrobenzaldehyde assay.In most instances comparable activity could not be demonstrated in vivo using the carrageenan foot edema method or the azovan blue-carrageenan pleural effusion method.α-5-Diphenyl-2H-tetrazole-2-acetic acid, m-[(α-phenylphenacyl)amino]benzoic acid, m-[3-(2,4-dioxo-1H,3H-quinazolinyl)]benzoic acid, 5,5'-selenobis salicylic acid, 3-octylsalicylic acid, N-acetyl-p-aminophenol are representative of the 42 acids with in vitro antiinflammatory effects.