An animal model of chronic enteroviral infection was established by using PCR to detect viral genomes in animal tissues and to compare levels of transcription of a variety of cytokines in the brain. Chronic coxsackie-virus B1 infection was found in both brain and skeletal muscle of mice infected as neonates. The viral infection cleared by 240 days post-infection. Elevated levels of tumour necrosis factor alpha and interleukin-6 (IL-6) would appear to be linked to acute and chronic infection respectively. Levels of IL-6 return to normal upon clearance of the virus.