This study is a multi-centre, non-interventional, observational, prospective study with retrospective analysis. The main purpose of the study is to describe the rate of CKD diagnosis in patients with AH and CKD markers. This study will include 10 000 adult outpatients with arterial hypertension, who have one or more Chronic Kidney Disease laboratory markers (without recorded CKD diagnosis prior to enrolment) and have no diabetes mellitus or symptomatic chronic heart failure, who are monitored and treated by cardiologists or internal medicine specialists in approximately 50 outpatient sites in about 20 regions in Russia. This observational study does not provide for any diagnostic and therapeutic procedures other than those used in routine practice.