To search for more potent antitumor agent, a series of novel nitric oxide-donating colchicine (Col) derivatives (6a-f, 8a and b) were synthesized by coupling nitrates with N-methyl colchiceinamide. Their cytotoxicity against four human cancer cell lines in vitro were evaluated by MTT assay. It was found that many of the derivatives displayed significant activity, particularly, compounds 6c, 8a and 8b showed more potent cytotoxic activities than Col.