Purpose The purpose of this study was to investigate the effects of proprioceptive neuromuscular facilitation(PNF) intervention for temporomandibular joints and hamstring on active mouth opening and hamstring flexibility. Methods 17 healthy adults were included in this randomized, single blind, crossover design study. The possibility of carry over effect could not be excluded. Before and after intervention, forward flexion distance, popliteal angle and active mouth opening were evaluated and results were analyzed. After first participating in the proprioceptive neuromuscular facilitation(PNF) intervention for temporomandibular joints, each subject visited again after a week to prevent the carryover effect and then participate in the other intervention. Results Both proprioceptive neuromuscular facilitation(PNF) intervention significantly improved forward flexion distance, popliteal angle and active mouth opening. Comparing the two intervention, TM joint intervention significantly improved popliteal angle. Hamstring intervention significantly improved active mouth opening. No significant differences in forward flexion distance test were found between interventions. Conclusion Although proprioceptive neuromuscular facilitation(PNF) intervention on hamstring had a effect on indirect intervention of active mouth opening, it is considered that more study is needed for clinical application.