Negative emotional states induced with electrical stimulation of ventro-medial hypothalamus (VMH) or with behavioral conflicts were followed by vascular pressor responses tending to sum up. Positive emotional states were followed mainly by pressor-depressor vascular responses in animals. Obvious disorders of cardio-vascular functions occurred in experimental-emotional stress, vascular responses to the VMH stimulation being mostly of the pressor character. Changes in vascular tone were shown to play a major part in disturbances of the AP regulation in the immobilization stress, a progressing fall in the AP due to a sharp decrease in total peripheral resistance being the main reason of the animals' death. The resistance of cardio-vascular functions against emotional stress seems to be determined mainly by genetic mechanisms.