Matrix metalloproteinases (MMPs) play vital roles in many pathological conditions, including cancer, cardiovascular disease, arthritis and inflammation. Modulating MMP activity may therefore be a useful therapeutic approach in treating these diseases. Qing-Kai-Ling is a popular Chinese anti-inflammatory formulation used to treat symptoms such as rheumatoid arthritis, acute hypertensive cerebral hemorrhage, hepatitis and upper respiratory tract infection. In this paper, we report that one of the components of Qing-Kai-Ling, Fructus gardeniae, strongly inhibits MMP activity. The IC50 values for the primary herbal extract and water extract against MMP-16 were 32 and 27 microg/ml, respectively. In addition, we show that the herbal extracts influence HT1080 human fibrosarcoma cell growth and morphology. These data may provide molecular mechanisms for the therapeutic effects of Qing-Kai-Ling and herbal medicinal Fructus gardeniae.