The authors present the results of clinical trail about treatment of arterial hypertension with ENAP (Enalapril) fo KRKA in centers of Bulgaria. Enalapril is ACE-inhibitor usually administered orally once daily, decreases blood pressure by lowering peripheral vascular resistance without increasing heart rate or output. In this clinical trail are given results about blood pressure, heart rate and biochemical indexes. The most frequent adverse events--headache, dizziness, orthostatic effects, abdominal pain e.t.s. occurring in less than 10%. More important side effects like dry persistent cough occurring in 8.6%. The results of clinical trail define high efficacy and good tolerability of ENAP in the treatment of arterial hypertension.