About forty years ago, immuno-targeting of antitumor drugs has been addressed as a way to improve their selectivity towards tumor cells. Despite the wide display of researches to solve inherent problems within this approach, rare were the immuno-conjugates which reached the clinical level. In any case, none of them was introduced in chemotherapy. However, there was a renewal of activity for the last ten years, due, in part, to the access to very highly cytotoxic-containing immuno-conjugates such as those elaborated from maytansinoides, enediynes or intercalating agents CC1065. It was also due to the design of the Adept concept. This antibody-directed enzyme prodrug therapy is based upon the use of monoclonal antibody to target an enzyme at the tumor cell surface which ultimately is expected to selectively deliver an antitumor drug from a suitable inactive prodrug. In both cases, clinical trials are in progress and one can expect that, at least, some immuno-conjugates will be soon introduced in cancer chemotherapy.