Extracellular matrix component is degraded by enzymes of thematrix metalloproteinases(MMPs). MMPs are produced by both hemopoietic and structural cells. Increased activity of MMP-3 in periodontium is strongly associated with inflammatory periodontal disease. The purpose of the present study was to estimate the effect of BMP-7 on regeneration of periodontium. The optical density was measured by microwell plate reader at 450 nm.The difference of the optical density and the relative activity ofMMP-3 according to the concentration were statistically analyzed by one way ANOVA. The results were as follows: 1. Tetracycline-HCl showed the tendency to inhibit the activity of MMP-3 at the concentration lower than $25{mu}g/ml$. 2. Doxycycline-HCl inhibited significantly the activity of MMP-3 at the concentration lower than $100{mu}g/ml$. 3 . Minocycline-HCl inhibited the activity of MMP-3 at the concentration in the range of 10 to 200${mu}g/ml$. Within the limit of the present study, the above results suggested that bone morphogenetic protein-7 may play a important role in development of periodontium.