Objective: To evaluate valsartan monotherapy effects on structural and functional characteristics of small-caliber vessels in patients with uncomplicated arterial hypertension (AH). Design and method: 35 patients (age 52,4 ± 2,1 years; male – 54,3%) with untreated uncomplicated grade I-II AH are included into the study. All patients were treated by valsartan 320 mg during 8 weeks. At baseline and after 8 weeks the parameters of microcirculation were measured. The parameters of microcirculation were evaluated by laser Doppler flowmetry: index of microcirculation (IM, perf.units), which characterizes basal blood flow; occlusion test - capillary blood flow reserve (CBFR), which characterizes the reversibility of remodeling microvasculature; difference index of microcirculation (DIM), which indicates the degree of reduction in blood flow during occlusion; half-recovery time of capillary blood flow (T1/2,s), which characterizes the reactivity of the vascular bed; index of increase in capillary blood flow (IICBF, perf.units), which indicates an increase in vasoconstriction. Data presented as M ± m. Wilcoxon criteria for by-pair comparisons was used. p < 0,05 was considered significant. Results: In patients with uncomplicated arterial hypertension was dominated spastic hemodynamic type of microcirculation (SHTM), identified in 68,6% of patients. After 8 weeks of treatment BP decreased from 158,5 ± 2,0/99,8 ± 0,6 mmHg to 142,2 ± 3,4/86,6 ± 2,0 mmHg (p < 0,001). 51,4% of surveyed have reached target BP levels < 140/90 mmHg. 21,9% responded to treatment determined as decrease in systolic BP >20 mmHg or diastolic BP>10 mmHg. Significant increase (p < 0,05) of IM, DIM, IICBF, T1/2 was observed: IM increased from 3,25 ± 0,22 perf.units to 3,89 ± 0,26 perf.units, DIM increased from 1,29 ± 0,37 perf.units to 2,22 ± 0,43 perf.units, IICBF increased from 5,82 ± 0,91 perf.units to 7,47 ± 0,51 perf.units, T1/2 increased from 22,8 ± 3,2 sec to 33,7 ± 3,0 sec. CBFR decreased from 393,7 ± 23,2% to 322,8 ± 29,3% (p < 0,05). Conclusions: Valsartan monotherapy (dose – 320 mg), 8-weeks course, contributes to reduction in microvascular reactivity, to increase of functioning microvessels and normalizes microcirculation response to arterial occlusion.