Cytolytic T-lymphocytes (CTL) can be repeatedly stimulated in L5178Y cell tumor-dormant DBA/2 mice by the i.p. inoculation of 2 X 10(6) X-irradiated L5178Y cells. The restimulated CTL activity has the same kinetics of generation and decline and the same target cell specificity as does the CTL response generated during establishment of the L5178Y cell tumor dormant state. No increase in adherent cell-mediated cytolytic activity or cytolytic or cytophilic anti-L5178Y antibody can be detected after inoculation of irradiated L5178Y cells. The repeated stimulation of CTL activity in tumor-dormant DBA/2 mice results in the elimination of L5178Y cells from a significant number of tumor-dormant mice.