This paper presents an analysis of publications, mostly by Soviet authores, on clinical studies and morphological examinations of the microcirculatory bed in different pathology. It is concluded that the microcirculatory bed should be regarded as an integral system responding to the pathological effects by a local and general reaction of its structural components and by changing the rheological properties of blood. Two types of changes develop in the microcirculatory system -- sterotyped ones, typical for extreme states (various kinds of shock, hypertensive crisis, stress situations), and those specific for certain diseases (diabetes melitus, essential hypertension, athersclerosis, collagenoses, etc.). In all the above diseases the pathological process affects the functional structures of microcirculation that undergo a rearrangement in accordance with the requirements of the body. In the initial period of the disease this re-arrangement is of a compensatory nature and passes ahead of the clinical manifestations. A comparison of the pictutrs obtained by biomicroscopy of the bulbconjunctiva of the eye and of other mucosae with film preparations of the serosae demonstrates their complete similarity. Therefore, the method of biomicroscopy of the eyeball and of the mucosae as a method reflecting the state of microcirculation in the body as a whole should become an integral part of the clinical examination of patients.