In the last two decades the problem of arterial hypertension in patients in the developmental age gained an increasing interest. The frequency of arterial hypertension in children was estimated at the level of 1-5% of the population. It was demonstrated that hypertension is observed in patients with type 1 diabetes over two-three times more frequently than in the general population. Arterial hypertension is a significant risk factor for cardio-vascular complications. The coexistence of diabetes type 1 and arterial hypertension predisposes to ischemic heart disease, stroke and premature death. Normal range of arterial tension for children was established during the Task Force on Blood Pressure Control study in children. Models depending on age and sex were created. Measurements above the 95 percentile for age and sex were referred to as significant hypertension and above the 97 percentile as heavy hypertension. For the development of arterial hypertension in patients with type 1 diabetes, which is the dominant type in children and adolescents, apart from the genetic predisposition, the coexistence of nephropathy is important. In children and adolescents almost exclusively secondary nephrogenic hypertension is observed, which develops usually 2 years after microproteinuria. Seldom in children and adolescents with type 1 diabetes essential hypertension or hypertension of other causes, as for example contraction of the nephrotic artery, may be observed. A particular form of arterial hypertension is lack of pressure decrease during the night, with a maintenance of the normal rhythm during the day. Recently the state called "pre-hypertension", considered as a precursor of hypertension and a predictor of excessive cardiovascular risk, has gained increasing interest. The pharmacological therapy of arterial hypertension in patients with diabetes type 1 may be taylored individually, depending on the degree and form of diabetes, and also on its late complications. In case of an unfavourable course dialysis may be considered and transplantation of the kidney, as hemodialysis in children with type 1 diabetes is connected with frequent complications. It is crucial to consider the transplantation of the kidney at early stages, when the creatinine level is above 5 mg/dl. It has been proved that the results of transplantation in patients with diabetes are similar to those in patients without diabetes.