The effects of biofeedback training and voluntary control procedures on heart rate and subjective reactions to 30-sec immersion of the hand in ice water were investigated in five experimental conditions, nine subjects in each condition. All subjects were given an initial cold pressor test and a final test interspersed by the particular condition. In two of the conditions, subjects were given biofeedback training for increasing or for decreasing heart rate. No training was given to the other three groups. In two of the latter conditions, subjects were simply asked to increase or decrease their heart rate during the second cold pressor test, without previous training. The fifth condition was a no-treatment habituation control. Significant variations between groups were obtained of the tachycardia and reports of pain associated with the second cold pressor test. In general, there was a correspondence between heart rate change and subjective report of pain. Voluntary control of heart rate or other autonomically-mediated responses, enhanced by biofeedback training, may have implications for research on and clinical management of physiological and subjective reactions to stressful stimuli.