The microvasculature (MV) of serous membranes was compared in rats with spontaneous genetic hypertension (SHR) and in normotensive Wistar rats. The study showed that in hypertension MV lesions had a systemic distribution, as structural changes were present in every MV component (arterioles, precapillaries, capillaries, postcapillaries, venules, lymphatic capillaries, and postcapillaries, nerve fibers); these lesions were generalized, as similar alterations could be found in all serous membranes studied. A close resemblance observed between MV of serous membranes in SHR and in patients who died of hypertensive disease confirms the concept suggesting the existence of MV changes which were relatively specific for hypertension, along with those of the nonspecific nature. Specificity of the hypertensive process is manifested in severe vascular lesions of a peculiar type, while the nonspecific phenomena are represented by a combination of intravascular, perivascular, and minimal vascular alterations represented by a universal MV response to various stresses.