This preliminary study investigated the psychoneuroimmunological effects of Korean Qi-therapy (QT) on randomly divided placebo group (N = 10) and QT group (N = 10) via measuring the level of anxiety, mood, cortisol and melatonin, and the cellular function of neutrophil and NK cells. Although the basal levels of anxiety and mood were not different between the two groups, there were significant differences in group by time interaction in the anxiety level (5 min after intervention, Post I: changed by −23 per cent in QT group and −10 per cent in placebo; 1 hour after, Post II: −23 per cent, −8 per cent) and mood score (Post I: −34 per cent, −14 per cent; Post II: −55 per cent, −21 per cent). Melatonin levels also changed differently by intervention. In response to QT, melatonin levels increased after treatment but decreased in the control. For neutrophil response to intervention, superoxide generation was increased by QT but decreased by placebo (group by time interaction, p < 0.0001; changed by 36 per cent in the QT group and 8 per cent in the placebo group). There was a significant change in NK cell cytotoxicity in the QT group. The cytotoxicity increased (27 per cent compared to baseline) in the QT group but there were no changes in the placebo group (7 per cent). Our current observations suggest that Korean Qi-therapy may induce psychological stabilization, increase melatonin level and enhance cellular function of neutrophil and NK cell. Therefore Qi-therapy may be an effective complementary method for human health care and in the prevention of disease. Copyright © 2001 John Wiley & Sons, Ltd.