Acupuncture points (APs) are well known to be small regions of local or referred pain that are more sensitive than surrounding tissue. Based on bibliographical and clinical data, specific conditions are commonly believed to change the pain sensitivity at corresponding APs. The aim of the present study was to investigate whether the pressure pain threshold (PPT) of specific APs is associated with the severity of premenstrual syndrome. The 46 participants were female students attending a middle school. Premenstrual syndrome (PMS) was measured using a structured questionnaire, the menstruation distress questionnaire (MDQ). High PMS (HP) and low PMS (LP) groups were divided based on their MDQ scores. The PPTs at sites in the leg (the APs SP6, GB39, and LR3 and a non-AP 2-cm anterior to SP6) and in the arm (the APs PC6, TE5, and LI4 and a non-AP 2-cm proximal to PC6) were measured using an algometer. The PPT of the HP group at SP6 was significantly lower than that of the LP group (13.50 ± 0.73 vs. 16.30 ± 0.66 kilopascals, P < 0.05), but not at other APs or at non-APs. The findings of our study support the hypothesis that the alteration of pain threshold at specific APs is associated with the severity of corresponding diseases. Further studies are needed to determine whether an observation of pain sensitivity at the APs could be used as an adjunctive tool for the diagnosis of a clinical problem.Key words: acupuncture, threshold of pain, somatosensory stimulation, premenstrual syndrome.According to classic traditional Chinese medicine theory, the functions of the human body are controlled by a vital force or energy called "Qi," which circulates among the organs along channels called "meridians" [1]. Although acupuncture points (APs) located along these meridians are at the core of acupuncture practice, pathophysiological explanations for these concepts remain elusive. APs are not only identified subjectively as tender points, but are also endowed with unique electrical properties, suggesting that they are functional rather than structural entities. Skin surface sites corresponding to APs possess increased electrical conductivity compared to surrounding sites, and "abnormal" values at APs are regarded as indicators of dysfunction in the related meridians and organs. Prior studies have demonstrated correlations between alterations in electrodermal measurements at specific APs and disease states [2,3]. Although considerable efforts have focused on explaining the change in electrical resistance at the corresponding APs under specific conditions, the hyperalgesic responses of the corresponding APs remain unknown.Each acupuncture point communicates with a visceral organ and reflects the conditions of that organ [1]. When the organs are subjected to pathophysiological changes, one or more of the related APs become tender (hypersensitive) or show other signs of abnormality, such as altered color or hardness of the skin [4]. Physical and psychological symptoms of premenstrual syndrome (PMS) are believed to affect up ...