Camptothecin (CT) glyco-conjugates of formula (I), containing a 3-O-methylated beta -L-fucose residue bonded to the 20-hydroxy group via a thiourea-modified peptide spacer, and their salts, stereoisomers and stereoisomer mixtures, are new. R1 = sterically hindered (i.e. beta - or psi -branched) non-polar side-chain of an aminoacid; R2 = basic-side-chain of an aminoacid; and Q = a group of formula (a)
