Purpose: The purpose of this study was to investigate the immediate effect of low-intensity pulsed ultrasound (LIPUS) used at several intensities on chondrocyte metabolism by gene expression analysis. Methods: Chondrocytes were isolated from the knee joint of 12-week-old Wistar rat. In order to induce osteoarthritis (OA) -like condition experimentally, interleukin-1β (IL-1β) of 0 pg/ml, 100 pg/ml and 1000 pg/ml concentration was added to the isolated chondrocytes. Then the chondrocytes were stimulated for 20 min by LIPUS of 0, 7.5, 30 and 120 mW/cm² intensity. After stimulation, gene expression analysis was conducted. Results: Matrix metalloproteinase (MMP) -13 mRNA expression, articular cartilage degeneration factor, induced by IL-1β at a concentration of 100 pg/ml was inhibited in an LIPUS intensity-dependent manner. Type 2 collagen and aggrecan mRNA expression, main articular cartilage matrix component, showed the inhibiting tendency by LIPUS stimuli. Conclusions: Our results suggest that LIPUS may potentially protect articular cartilage by inhibiting MMP13 mRNA expression in an intensity-dependent manner.