A series of 1,3-benzodioxoles (5-19) was synthesized and evaluated for their in vitro antitumor activity against human tumor cell lines. Some derivatives exhibited tumor growth inhibition activity. In particular, 6-(4-aminobenzoyl)-1,3-benzodioxole-5-acetic acid methyl ester 8, the most active compound of the series, possesses a significant growth inhibitory activity on 52 cell lines at concentrations ranging from 10(-7) to 10(-5) M.