Background: Isolated systolic hypertension (ISH) is a major cause of morbidity and mortality. This study evaluated the effectiveness of treatment with an indapamide/amlodipine single-pill combination (SPC) in outpatients with uncontrolled ISH aged over 55 years in real-life clinical practice.Methods: This was a post-hoc analysis of the subgroup of patients with ISH from ARBALET, a 3-month, multicenter, observational, open-label study conducted in Russia among patients with grade I or II hypertension who were either uncontrolled on previous antihypertensive treatment or treatment-naïve. The effectiveness of indapamide/amlodipine SPC was assessed by the change in office systolic blood pressure (SBP) and the rate of target SBP (<140 mmHg) achievement at 2 weeks, 1 month and 3 months, in four age groups: 55-59 years, 60-69 years, 70-79 years, and 80 years or older.Results: The ARBALET study recruited 2217 patients, of whom 626 had ISH and were included in this post-hoc analysis (mean age 66.1±7.8 years; 165 men [26.36%] and 461 women [73.64%]). Target SBP <140 mmHg was achieved in 43%, 75% and 93% of patients at 2 weeks, 1 and 3 months, respectively. SBP decreased from baseline by 18.8±10.5 mmHg, 27.2±10.6 mmHg and 31.8±9.9 mmHg at 2 weeks, 1 month and 3 months, respectively. In the groups of patients aged 55-59, 60-69, 70-79, and ≥80 years, SBP reductions at 3 months compared with baseline were -30.3±9.4, -32.4±9.7, -32.5±10.7, and -28.9±9.6 mmHg, respectively. Conclusion: This post-hoc analysis of the observational ARBALET study showed that indapamide/amlodipine SPC was associated with significant reductions in BP and high rates of target BP achievement in a broad age range of patients with ISH treated in routine clinical practice.Trial registration number: ISRCTN40812831