The aim of the present study was to evaluate the efficacy and safety of S-amlodipine 2.5 and 5 mg/d in patients with hypertension who were treatment-naive or previously received antihypertensive monotherapy. During the 8-week treatment period, all patients received S-amlodipine 2.5 mg/d for the first 4 weeks, followed by S-amlodipine 5 mg/d for the second 4 weeks. For efficacy assessments, ambulatory and office blood pressure (BP) measurements were performed during the baseline, fourth-week, and eighth-week visits. For safety assessments, all adverse events and abnormal laboratory findings were recorded. This study is registered with ClinicalTrials.gov (NCT03038451). Of 43 patients evaluated at the screening visit, 33 were enrolled. In the treatment-naive arm, significant reductions in both office and ambulatory systolic BP (SBP) and diastolic BP (DBP) were observed with S-amlodipine 2.5 mg/d and additional significant reductions were achieved with dose titration (S-amlodipine 5 mg/d). At the end of the study, the rate of the treatment-naive patients with BP under control (SBP/DBP <140/90 mm Hg) was 53% with S-amlodipine 2.5 mg and increased to 78% with S-amlodipine 5 mg. For the noninferiority evaluation, S-amlodipine 2.5 and 5 mg/d treatments were generally noninferior to both office and ambulatory BP levels achieved with the medications that the patients received before participating in the study. Five nonserious adverse events likely to be associated with the study drug were observed. No serious adverse event was encountered. Consequently, S-amlodipine can be suggested as an effective and safe treatment option for patients with hypertension.