Polymerase chain reaction (PCR) technique was applied for detection of picornavirus genomes in blood and myocardial tissue of patients with viral myocarditis. Additionally, the blood and myocardial tissue of rabbits infected by picornavirus was also screened by PCR. Twelve rabbits infected by piocrnavirus showed pathological change of myocarditis and all of these animals gave a positive PCR result for picornaviral RNA sequences in the blood and myocardial tissue. All 6 control rabbits gave no PCR positive signals. PCR gene amplification actually provides a new diagnostic approach to patients suspected of viral myocarditis.