Liposomes were coated with subunits of murine IgM monoclonal antibody and used as the carrier of an anti-cancer drug. The antibody-coated liposomes containing an anti-cancer drug (chemoimmunoliposomes, CIL) were prepared by using dactinomycin and monoclonal antibodies against a human bladder cancer or a mouse mammary cancer. These CIL exhibited antigen-specific binding to the target cancer cells, and there was more efficient killing of the target cancer cells than with free dactinomycin. In the mouse mammary cancer model, the CIL showed a therapeutic effect in both local and systemic applications. Relevance of this CIL model to cancer therapy and the problems related to its development are discussed.