The gene for the human melanoma-associated antigen p97 has been introduced by cDNA transfection into cells from clone M2 of the K1735 mouse melanoma, which metastasizes to the lung when injected iv into syngeneic C3H/HeN mice. Tumor clones were established from the transfected cells and found to differ in the level of p97 expression. Their outgrowth in immunocompetent syngeneic mice was shown to inversely correlate with p97 antigen expression, and lines that express higher p97 levels elicited a stronger delayed-type hypersensitivity response when injected into the footpads of mice immune to p97. Five clones which expressed very high levels of p97 failed to grow in immunocompetent C3H/HeN mice while they formed tumors in nude (nu/nu) mice. The highest expressing clone, 2A, grew slightly faster than any of the other clones when cultured in vitro. Since several of the transfected clones were found to express a stable level of p97 and have consistent in vivo growth behavior, they provide a useful model for various forms of antigen-specific active and passive immunotherapy with the same agents as those intended for human application.