The present invention relates to novel colchicine derivatives having antiproliferative, antineoplastic, antiinflammatory and muscle relaxant activities; said derivatives include novel colchine nitrogen amides for use either as such or after derivatization of the hydroxyl at C.sub.3 of the aromatic ring and at C.sub.10 of the tropolone ring. These novel compounds have a cytotoxicity on human tumoral cell lines comparable with colchicine but, in comparison with the latter, they are much more active on cells resistant to the usual antiblastics. The compounds can be included in pharmaceutical formulations useful for the intravenous, oral and topical administrations.