A new series of 1,5-disubstituted indolin-2,3-diones was synthesized and their inhibition of the growth of a human acute promyelocytic leukemia (HL-60) cell line was evaluated. These compounds had promising inhibition of HL-60 cell growth in vitro. Results indicated that compounds with a benzyl substituent at the N-1 position on the indolin-2,3-dione ring had more potent antiproliferative activity than those with a (4-fluorobenzyl) amino-2-oxoethyl substituent at the N-1 position. Among the compounds synthesized, compound 8l inhibited half of cell growth at a concentration of 0.07 μM and compound 8p did so at a concentration of 0.14 μM. These compounds may serve as lead compounds for further optimization in order to develop novel anticancer agents.