BACKGROUND: Changes in extracellular of chondrocyte can reflect influence of external force on temporomandibular joint and adaptability of body to external force. OBJECTIVE: To study the effect of cyclic tensile stress on main extracellular matrix of condylar chondrocyte.METHODS: The cyclic tensile stress was exposed to the third passage condylar chondrocyte for 0, 1, 6, 12 and 24 hours, respectively, using a Flexcell Strain Unit-5000T system (10% surface elongation, 6 cycles/min). After mechanical loading, total RNA was extracted from the cells harvested from Six-well BioFlex flexible cell Petri Dish, reverse transcribed, and reverse trabscription-PCR was performed to quantify mRNA levels for type Ⅱ collagen and aggrecan.RESULTS AND CONCLUSION: Compared with the control group (0 hour group), both type Ⅱ collagen and aggrecan mRNA expression was significantly increased after loading for 6 hours (P < 0.05), but began to decrease since 12 hours, and significantly decreased at 24 hours (P < 0.05). Results showed that cyclical tensile stress stimuli can affect the synthesis of main extracellular matrix of condylar cartilage, i.e. the synthesis was gradually enhanced with prolonged stimulation duration, but significantly inhibited in response to further stress stimuli.