The conjugation of the drugs with vector molecules enables to obtain therapeutic preparation, which may be transported to the selected target organ. In the present work the methods of conjugation of antineoplastic enzyme L-lysine α-oxidase with antibodies were elaborated. Conjugates were worked out through the attachment of amino groups on the antibody surface either with the aldehyde groups which were created in L-lysine α-oxidase molecule (0.2% of initial enzymatic activity) or with the aldehyde groups of cross-linking molecules. Maximal (78%) L-lysine α-oxidase activity in conjugates was observed when oxidized peroxidase which contained the aldehyde, groups was used as crosslinking agent. The glutaraldehyde method yielded 70% of initial enzyme activity.