Our recent studies showed that one session of transcutaneous electrical nerve stimulation on acupoints (Acu-TENS) improved forced expiratory volume in 1s (FEV(1)) in patients with chronic obstructive pulmonary disease (COPD). This study investigated the effect of 4-week Acu-TENS on physical and psychosocial function in these patients. Twenty-eight patients were randomly allocated to receive 4-weeks of 45-min, 5-days/week, of either Acu-TENS (over Dingchuan), Placebo-TENS (same protocol without electrical output), or Sham-TENS (over the patellae). Variables measured before and after intervention included FEV(1), forced vital capacity (FVC), 6-min walk distance (6MWD), St. George's Respiratory Questionnaire score (SGRQ), beta-endorphin and blood inflammatory marker levels. Only the Acu-TENS group attained significant improvement in FEV(1) (p=0.046), physical activity (p=0.007) and total SGRQ score (p=0.028). The increase in beta-endorphin (p=0.012) correlated positively with the improvement in FEV(1) (r=0.526, p=0.008). To conclude, 4 weeks of Acu-TENS improved the functional capacity of patients with COPD, probably due to the bronchodilation induced by beta-endorphin elevation.