The purpose of this study was to compare the integrated electromyographic activity ratios of vastus lateralis(VL); rectus femoris lateral portion (RFL); rectus femoris medial portion(RFM); and vastus medialis(VM) muscles of 30 healthy subjects under three proprioceptive neuromuscular facilitation(PNF) techniques. Each subject was randomly assigned to one of 3 PNF techniques groups : slow reversal(SR), slow reversal hold(SRH) and rhythmic stabilization (RS). Each person was positioned in supine with the right hip flexed to $45^{circ}$ and the knee fully extended and received a total of 6 sessions. Each technique was applied to the right lower extremity in two diagonal patterns while electrical activity was monitored from the ipsilateral muscles VL, RFL, RFM, and VM, respectively. Comparison of normalized mean EMG magnitudes from VL, VM showed that RS demonstrated significantly greater activity than that of SR or SRH and that RFL and RFM did not demonstrate any greater relative EMG activity with the three PNF techniques than did VL or VM.