OBJECTIVE: To explore the relationship between the theory of constitution in terms of Chinese medicine and clinical efficacy of acupuncture treatment via analyzling the characteristics of Deqi during acupuncture stimulation of Zusanli (ST 36) in healthy volunteers with different constitutions. METHODS: In the present study, a total of 527 healthy undergraduate student volunteers (267 girls and 260 boys) were recruited. They received questionnaire first about their constitutions in accordance with Professor WANG Qi's Classification and Determination of Constitution in terms of Chinese medicine. Then, the subjects were asked to take a supine position on a check-bed, a qualified acupuncturist held a sterilized fifiform needle to rapidly insert it into ST 36 and manipulated the acupuncture needle with uniform reinforcing-reducing technique at a frequency of about 60-90 times/min and an amplitude of 0.3-0.5 cm. The status of Deqi was assessed by using visual analogue scale (VAS). RESULTS: Needling sensations mainly involve soreness, numbness, heaviness, distension, dull pain and propagated sensations along meridian (PSC). During acupuncture stimulation, most subjects experienced distension sensation, accounting for 90.3%, followed by soreness, accounting for 45.9%. Except for PSC reaction, the rest 5 needling sensations had no statistical difference in their occurrence rates in those subjects with different constitutions (P>0.05). The PSC appeared a higher incidence in yin-yang harmony(balanced) constitution subjects than in qi- deficiency, yang-deficiency, blood-stagnation and qi-stagnation constitution subjects (P<0.05). The intensity of soreness was obviously stronger in the balanced constitution subjects than in qi-deficiency, yang-deficiency, yin-deficiency, phlegm-damp, damp-heat and qi-stagnation constitution subjects (P<0.05), while the intensity of distension sensation was apparently stronger in the balanced constitution subjects than in simpleyang-deficiency subjects (P<0.05). CONCLUSIONS: Except for PSC, the Deqi sensations of soreness, numbness, heaviness, distension and dull pain induced by acupuncture stimulation of ST 36 are comparable in the occurrence rates in healthy volunteer subjectswith different (9 types of) constitutions in terms of Chinese medicine, whereas the intensity of soreness may be the important factor for acupuncture induced pain relief. A certain correlation between the constitution and acupuncture effectiveness exists, suggesting that acupuncture treatment should vary from patient to patientin clinical practice.