Insulin resistance (IR) appears to be an important risk factor of both hypertension and atherosclerosis. Moreover, it is present also in obesity, dyslipoproteinaemia and non-insulin dependent diabetes. IR could be found in untreated hypertension and even in normotensive children of hypertensive parents. It alters carbohydrate, lipid and protein metabolism and participates directly in the development of hypertension. The diagnosis of IR is possible by simple determination of insulin and glyceamia during glucose tolerance test. The differential diagnosis is obligatory because IR is not specific just for hypertension. Treatment, with the exception of nonpharmacological measures, is unsatisfactory. However, results of newest research are highly promising.