Aim. To study the efficacy and safety of the triple fixed-dose combination (FDC) of amlodipine/indapamide/perindopril on blood pressure (BP) profile in patients with grade I-II hypertension (HTN) in actual clinical practice.Material and methods. Data from 54 patients with paired 24-hour ambulatory BP monitoring (ABPM) data were included in the TRICOLOR subanalysis (ClinicalTrials. gov study ID — NCT03722524). The mean 24-hour, daytime, and nighttime BP were calculated at baseline and after 12-week follow-up. We determined the proportion of patients with nocturnal HTN (≥120/70 mm Hg) and nocturnal hypotension (<100/60 and <90/50 mm Hg) initially and after 12 weeks of triple FDC therapy. Patients with nocturnal BP decrease included dippers (D; 10-20%), reduced dippers (RD; 0-10%) and extreme dippers (ED; >20%), as well as those without nocturnal BP decrease (>0%, non-dipper (ND)). The smoothness index (SI) was analyzed as the ratio of the mean hourly SBP fall to its mean standard deviation in paired ABPM. To assess the BP phenotypes, two methods were used with reference values of <130/80 and <140/90 mm Hg for ABPM and office BP, respectively. Controlled hypertension (CHT), uncontrolled hypertension (UHT), white coat hypertension (WHT) and masked ineffectiveness of antihypertensive therapy were distinguished.Results. Among 1247 participants of the TRICOLOR study, 54 patients with valid paired ABPM were selected (men, 46%; mean age, 57,7 [12,1] years; mean office BP, 150,4 [16,6]/93,3 [10,7] mm Hg; HTN duration, 8,3 [7,5] years). Initially, the mean 24-hour, daytime and nighttime BP was 141,1 [15,4]/85,9 [9,9], 144,2 [15,5]/88,8 [10,5] and 132,6 [18,0]/78,1 [9,9] mm Hg, respectively. After 12-week follow-up, the mean 24-hour, daytime and nighttime BP was 123,1 [10,5]/75,6 [8,5], 125,7 [10,9]/77,9 [8,7] and 115,4 [10,2]/68,6 [8,8] mm Hg, respectively (p<0,001). After 12-week follow-up, the proportion of patients with nocturnal hypertension decreased from 64,8% to 25,0% (2,6 times) (p<0,001). The proportion of NDs and EDs decreased from 16,7% and 7,4% to 5,8% and 0%, respectively (p=0,048); the proportion of patients with RD and D patterns increased from 42,6% and 33,3 to 57,7% and 36,5%, respectively (p=0,048). With triple FDC therapy, the SI during the day was higher than 0,73 in half of the cases. According to the two methods, the proportion of patients with UHT decreased from 81,6% to 4,4%, WHT from 12,2% to 0%. The prevalence of CHT increased from 4,1% to 57,8%, while masked ineffectiveness of antihypertensive therapy — from 2,0% to 37,8%.Conclusion. Twelve-week FDC therapy of amlodipine/indapamide/perindopril led to a significant fall in the mean 24-hour, daytime and nighttime BP values. Comprehensive analysis of two techniques (24-hour and office BP measurement) identified patients requiring further triple FGC titration.