Dried rhizomes of Cimicifuga racemosa (CR), which are known as black cohosh, have been widely used as herbal dietary supplements to treat menopausal symptoms. The present study examined the effect of CR extracts on human psychological and physiological responses to acute stress induced by mental arithmetic tests, by measuring the subjective stress intensity, the brain-wave patterns according to electroencephalography, and the concentrations of salivary chromogranin-A and cortisol. The experiments were performed double-blind and their order was counterbalanced. Treatment with CR significantly attenuated the elevated subjective perception of stress and the increased salivary chromogranin-A levels compared with placebo treatment. CR extract also rapidly recovered the decrease in alpha waveband induced by performing the mental arithmetic task. We therefore propose that CR extracts might be suitable for the prevention and treatment of stressrelated disorders.