Conflicts amongst reports concerning the efficacy of both nonspecific and specific attempts at immunotherapy may be ascribed to different animal models utilizing tumors of different immunogenicity. We have selected the B16 mouse melanoma model as the example of a spontaneously occurring neoplasm that is histocompatible with the host and does have tumor-associated antigens. Attempts to alter tumor growth or survival with nonspecific active immunotherapy as well as with specific active immunotherapy were not successful. Nonspecific active pre-immunization failed to alter tumor take or growth. Specific active immunotherapy both with and without adjuvant did decrease tumor take and prolong host survival. The effects were increasingly documented at lower tumor cell inoculums and became less apparent with increase in the tumor cell challenge.