&NA;Using KHT tumor in a mouse metastatic tumor model. we examined the effect of intracerebral and/or intraperitoneal injections ofCorynebacterium parvumon the growth of metastatic brain tumor and the development of an inflammatory response in the central nervous system (CNS).C. parvumgiven intraperitoneally had no effect on the development and growth of CNS tumor, but did prolong the survival of mice by inhibiting the growth of systemic metastatic tumor, which was the cause of death in our tumor model. Mice that received intracerebral injections ofC. parvumexhibited significantly decreased growth of metastatic brain tumor, as compared with mice that received intracerebral injections of saline, whether or not they had receivedC. parvumintraperitoneally. In addition, the brains of mice that receivedC. parvumintracerebrally exhibited an inflammatory response that was minimal or absent in the brains of control mice. Our results suggest that if immunotherapeutic agents can be delivered to the CNS and cause an inflammatory response. they can be effective against CNS metastases. (Neurosurgery25:709‐714, 1989)