The first part of this review presents a historical outline on the development of experimental methods in electrophysiology starting from the first experiments performed in the 1920s and ending with the "patch-clamp" technique. Recording configurations of the "patch-clamp" technique are briefly reviewed in the second section. The areas of application of the configurations are shown. The last section contains a short review on the available data of "patch-clamp" studies on the expression and properties of potassium channels in human T lymphocytes (TL). Problems that require further investigation are briefly presented.