OBJECTIVE: To obtain the mean value of parameters of the jaw jerk and to investigate gender difference on the jaw jerk in normal young adults in Korea. METHOD: In young 40 subjects (20 males and 20 females), the jaw jerks were elicited by chin tapping in the relaxed masseter muscles of both sides. RESULTS: The jaw jerks were recorded in 100% of the total number of chin-taps. The mean latency was 5.39 ms in the males and 5.14 ms in the females (p>0.05). The mean amplitude was 0.75 mV in the males and 0.59 mV in the females (p>0.05). The mean duration was 8.18 ms in the males and 7.85 ms in the females (p>0.05). CONCLUSION: No significant differences were found in the parameters of the jaw jerk between males and females in this study.