A combined psychiatric, medical and physiologic study was made of 12 hospital patients who were in various stages of progression from benign to malignant hypertension. The psychiatric material included personal history, early memories, transference phenomena, dream content, and free associations. It was obtained in a series of "semi-directive" interviews. Clinical and physiologic responses to stimuli presented in the exptl. laboratory and to situations as they arose on the ward and in the general life environment were also recorded. In each of the patients "the precipitation of the malignant phase could be chronologically correlated with emotionally significant life situations or events." This was also the case in respect to the development of benign hypertension in those patients where the onset could be adequately detd. Illustrative case histories are included.