To examine the possible involvement of MMP-9 and -2 in the development of liver diseases caused by HCV or HBV infection, serum activities of both enzymes were studied by zymograph. Eight groups of subjects (60 for each) were examined in the study: healthy control, patients with hepatoma, liver cirrhosis, chronic hepatitis B or chronic hepatitis C, and carriers positive for HBsAg, both HBsAg and HBeAg, or anti-HCV. The results showed significant changes in the MMP-9 and -2 activities in the carriers. The presence of HBeAg was accompanied by a highest activity of MMP-2 and an inversely correlated (r=-0.578, P=<0.001), lowest activity of MMP-9 among all groups. For those with active liver diseases, MMPs activities were fluctuated at each stage of pathological symptoms. Chronic hepatitis B and C patients had significant different serum MMP-2 and -9 activities. These findings imply an influence on the balance of MMPs system by the existence of virus that might influence the following progression of liver disease, and a distinction between the pathological mechanisms of HCV and HBV. Since the serum MMPs activities were significantly varied between each stage of liver disease, an individual profile of these parameters might serve as an easy accessing serum marker to monitor the progression of liver disease.