Objective: To study the proliferative changes of cultured rat mandibular condylar chondrocytes effected by mechanical stress. Method: Flow cytometry (FCM) was used to explore the changes of cellular DNA content and cell cycles of passaged condylar chondrocytes. Results: FCM results indicated that proliferation of cultured rat mandibular condylar chondrocytes decreased with stress duration, with marked differences between the experimental and control groups. Conclusion: Within given force duration and force range (0-207g/an2), proliferation of rat mandibular condylar chondrocytes increased with force magnitude, reaching the maximum 6 hours after application of stress. Cellular proliferation decreased when the chondrocytes were cultured under continuous stress for 24 hours. The mechanism for these proliferative changes requires further study.