A series of 2,3-dihydrobenzofuran-5-acetic acids and related compounds was prepared as potential antiinflammatory agents. As measured by the carrageenan-induced edema method for the preliminary screening test, introduction of a methyl group alpha to the acetic acid function enhanced the antiinflammatory activity, and alpha-(7-chloro-2,2-dimethyl-2,3-dihydrobenzofuran)-alpha-methyl-5-acetic acid (13a) showed the most potent activity in this series.