The author made an examination, as a part of systematic studies on the effects of hot-spring bathing on the functions of the circulatory system in his institute, of the effects of gradually warming partial bathing apparatus by SUGIYAMA on the functions of the circulatory system with reference to the circulating blood volume and pulse rhythm, which led to the following conclusions.<br>1) In hypertensive patients average circulating plasma volume was 48.2±1.3ml/kg, circulating blood volume 83.4±2.0ml/kg, and circulating blood cell volume 35.3±0.9ml/kg, the range of distribution being wider than that of normal persons and each value was increased in most cases. No correlations seemed to be present between blood pressure and circulating blood volume.<br>2) In patients with normal blood pressure (13 cases) the pulse interval was 0.96±0.0697″, there being 11 cases (84.6%) of single-peak type and 2 cases (15.4%) of double-peak type. In hypertensive patients (24 cases), the pulse interval was 0.935±0.0543″, there being 20 cases (83.3%) of single-peak type and 4 cases (16.7%) of double-peak type. No remarkable difference could be observed between the two.<br>3) The examination of the effects of single bathing with reference to the circulating blood volume and pulse rhythm revealed that the magnitude of the effect is in the following order:<br>Steam bathing for hypertensive patients>steam bathing for normal pressure persons>gradually warming partial bathing for hypertensive patients>gradually warming partial bathing for nomal pressure persons.<br>This clearly shows that gradually warming partial bathing acts on the bather more mildly than steam bathing. This is generally observable in normal pressure persons, but individual difference is observable in hypertensive patients. For these reasons, the bathing effect is more unstable in hypertensive patients than in healthy persons.<br>4) With the progress of this gradually warming partial bathing cure, the changes in the circulating blood volume and pulse rhythm occurring after this single bathing decreased gradually. This is especially clear in the case of hypertension in which the changes are great and unstable. No definite tendency can be seen, however, in the steam bathing cure.<br>5) Consequently, the examination with reference to the circulating blood volume and pulse rhythm has confirmed that this gradually warming partial bathing is not only good for the function of the abnormal circulatory system, but also improves it.