AIM:Type IV collagenase participates in invasion andmetastasis of cancer cells.Malignant ascites is a manifestationof advanced malignant disease that is associated withinvasion and metastasis of the peritoneal cavity.Thus,it isreasonable to hypothesize that type IV collagenase is linkedto malignant ascites.The purpose of our study was to detecttype IV collagenase activity in malignant ascites so as toprovide the scientific basis for clinic diagnosis and treatmentof malignant ascites.METHODS:Cirrhotic ascites (n=36),tuberculous ascites(n=8) and malignant ascites (n=23) from patients withgastric cancer (n=6),colon cancer (n=5),ovarian cancer(n=8) and other cancers (n=4),including 2 hepatocellularcancers,1 pancreatic cancer,1 primary peritoneal carcinomawere collected by paracentesis.The ascites were made cell-free by centrifugation and stored frozen at-70 ℃ beforedetermination.Type IV collagenase activity was determinedby gelatin zymography.RESULTS:The activity of matrix metalloproteinases-2 and-9 could not be detected in ascites of hepatic cirrhosis andtuberculous peritonitis but could be detected in 20 and 18out of 23 malignant ascites respectively.The positive rateof type IV collagenase (MMP-2,87.0 % and MMP-9,78.3 %)was higher than that by routine ascites tests (P<0.01) inmalignant ascites.Furthermore,the activity of MMP-2 washigher than that of MMP-9 (P=0.022<0.05).CONCLUSION:Type IV collagenase is positive in malignantascites.Detection of type IV collagenase activity is useful inqualitative diagnosis of ascites.Type IV collagenase mayplay an important role in malignant ascites formation. AIM: Type IV collagenase participates in invasion and metastasis of cancer cells. Malignant ascites is a manifestation of advanced malignant disease that is associated withinvasion and metastasis of the peritoneal cavity .hus, it isreasonable to hypothesize that type IV collagenase is linkedto malignant ascites.The purpose of our study was to detecttype IV collagenase activity in malignant ascites so as toprovide the scientific basis for clinic diagnosis and treatment of malignant ascites. METHODS: Cirrhotic ascites (n = 36), tuberculous ascites (n = 8) and malignant ascites (n = 23) from patients with gastric cancer (n = 6), colon cancer (n = 5), ovarian cancer (n = 8) and other cancers (n = 4), including 2 hepatocellular cancer, 1 pancreatic cancer, 1 primary peritoneal carcinoma tissue collected by paracentesis. The ascites were made cell-free by centrifugation and stored frozen at -70 ° C beforedetermination.Type IV collagenase activity was determined by gelatin zymography .RESULTS: The activity of matrix metalloprotein ases-2 and-9 could not be detected in ascites of hepatic cirrhosis and tuberculous peritonitis but could be detected in 20 and 18 out of 23 malignant ascites respectively. The positive rate of type IV collagenase (MMP-2, 87.0% and MMP-9, 78.3 The activity of MMP-2 washigher than that of MMP-9 (P = 0.022 <0.05) .CONCLUSION: Type IV collagenase is positive in malignantascites (P <0.01) . Detection of type IV collagenase activity is useful in quantitative diagnosis of ascites. Type IV collagenase may play an important role in malignant ascites formation.