Aim. To evaluate the pharmacokinetics of amlodipine in patients with arterial hypertension. Design. Open cohort study. Materials and methods. The study included 183 patients, 98 of them with uncontrolled arterial hypertension and 85 with controlled hypertension. All patients regularly took any two antihypertensive drugs (AHD) (lisinopril, amlodipine, valsartan, metoprolol) in combination with indapamide for a month. In the morning, fasting, before taking AHD and 2 hours after taking amlodipine, venous blood samples were taken from all patients to test the concentration of the analyte using high-performance liquid chromatography with tandem mass spectrometry. Results. In terms of the main concomitant diseases, the patients of the two groups were comparable to each other. Only angina pectoris (p = 0.02) and overweight (p = 0.02) were statistically significantly more common in the pressure–controlled group, and less often — grade 2 obesity (p = 0.002) and acute cerebrovascular accident (p = 0.05). The daily dose of amlodipine in patients with controlled hypertension was significantly (13.9%) lower (p < 0.05) than in participants with uncontrolled hypertension. Both the steadystate concentration of amlodipine and the concentration 2 hours after administration in patients with uncontrolled hypertension were not statistically significantly different from those in patients with controlled hypertension (p > 0.05). In 65.6% of patients with uncontrolled and in 49.4% with controlled hypertension, the concentration of amlodipine was within the therapeutic range (p = 0.03), in 5.2% and 16.5%, respectively, it was above the therapeutic range (p = 0.016), in 29.2% and 34.1%, respectively, — below the therapeutic range (p > 0.05). Conclusion. Conducting therapeutic drug monitoring and assessing the pharmacokinetics of amlodipine in clinical practice may be useful to improve the effectiveness and safety of therapy. Keywords: arterial hypertension, antihypertensive drugs, amlodipine, high-performance liquid chromatography with tandem mass spectrometry.