Acupuncture is a useful tool to treat many diseases, including cardiovascular disorders, but its modulation of stress-related responses is still debated. Aim of this study was to estimate whether the traditional Chinese acupuncture affected the transient impairment of the brachial artery flow-mediated dilation (FMD) produced by acute mental stress. In addition, since a high susceptibility to hypnosis attenuates the endothelial dysfunction elicited by mental calculation, the possible interaction between acupuncture and hypnotizability was investigated. Five low-to-medium and five medium-to-high hypnotizable healthy subjects joined two experimental sessions, for real and sham acupuncture. FMD and heart rate were measured in three conditions: baseline (PRE), after the real or sham acupuncture (ACU) and after mental calculation (MS). Needles were inserted into specific acupoints for real acupuncture and into non-acupoints, corresponding to the same spinal segment, for sham acupuncture. Results showed that the stress-related endothelial dysfunction was not modulated by acupuncture, but influenced by hypnotizability. In fact, highly hypnotizable subjects did not present any dysfunction, at variance with non-susceptible individuals that exhibited the expected stress-related FMD reduction (Mean +/- SD; PRE, 12.10 +/- 2.59; ACU, 10.73 +/- 3.45; MS, 6.48 +/- 1.72). Thus, hypnotizability appears more effective than acupuncture in contrasting the stress effects on the endothelial function. In conclusion, our study indicates the importance of patients' psychological evaluation in order to choose proper relaxation techniques and to evaluate therapeutic results and the necessity to integrate the alternative medicine practice with scientific research.