Purpose In a prospective open study, with intervention, conducted in Primary Health Care Units by General Practitioners (GPs) in Portugal, the effectiveness of a single pill of candesartan/amlodipine (ARB/amlodipine), as the only anti-hypertension (anti-HTN) medication, in adult patients with uncontrolled HTN (BP > 140/or > 90 mm Hg), either previously being treated with anti-HTN monotherapies (Group I), or combinations with hydrochlorothiazide (HCTZ) (Group II), or not receiving medication at all (Group III), was evaluated across 12-weeks after implementation of the new therapeutic measure. Materials and methods A total of 118 GPs recruited patients with uncontrolled HTN who met inclusion/exclusion criteria. Participants were assigned, according to severity, one of 3 (morning) fixed combination candesartan/amlodipine dosage (8/5 or 16/5 or 16/10 mg/day) and longitudinally evaluated in 3 visits (v0, v6 and v12 weeks). Office blood pressure was measured in each visit, and control of HTN was defined per guidelines (BP< 140/90 mmHg). Results Of the 1234 patients approached, 752 (age 61 ± 10 years, 52% women) participated in the study and were assigned to groups according to previous treatment conditions. The 3 groups exhibited a statistically significant increased control of blood pressure after receiving the fixed combination candesartan/amlodipine dosage. The overall proportion of controlled HTN participants increased from 0,8% at v0 to 82% at v12. The mean arterial blood pressure values decreased from SBP= 159.0 (± 13.0) and DBP= 91.1 (± 9.6) at baseline to SBP= 132,1 (± 11.3) and DBP= 77,5 (± 8.8) at 12 weeks (p < 0.01). Results remained consistent when controlling for age and sex. Conclusion In patients with uncontrolled HTN, therapeutic measures in accordance with guidelines, with a fixed combination candesartan/amlodipine, allowed to overall achieve HTN control at 12 weeks in 82% of previously uncontrolled HTN patients, reinforcing the advantages of these strategies in primary clinical practice.