A series of amino acid-conjugates of 10-hydroxycamptothecin and 9-nitro-10-hydroxycamptothecin were synthesized by means of a two-carbon side chain from 10-hydroxycamptothecin. The cytotoxic activities of all the synthetic compounds on KB, HepG2 and C26 in vitro were evaluated by CCK-8 assay. The results revealed that part of the conjugates exhibit potent anti-proliferative activities against selected tumor cell lines. Among them, the amino acid-conjugates of 10-hydroxycamptothecin show more potent activities than those of 9-nitro-10-hydroxycamptothecin in vitro as antitumor agents.