OBJECTIVES: Despite the rising prevalence of hypertension and the availability of evidence-based guidelines for effective treatments, blood pressure (BP) control rates remain low. The purpose of this study was to evaluate the effect of telephone counseling intervention on blood pressure control. METHODS: Adults with hypertension attending the Centre for Diagnosis and Therapy of Arterial Hypertension of Cardarelli Hospital, Naples, Italy were randomly allocated to receive a pharmacist/counselor-administered counseling intervention (group I) or usual care (group C). Group I patients received the counseling intervention bi-monthly for two years via telephone; the goal of the intervention was to promote medication adherence and improve hypertension-related health behaviors. The telephone intervention focused on perceived risk of hypertension and knowledge, memory, medical and social support, patients' relationship with their health care provider, adverse effects of medication therapy, weight management, exercise, diet, smoking, and alcohol use. BP values were registered at baseline, after one year and at the end of the investigation for both groups. Medication adherence (Belief Medicine Questionnaire, BMQ) was also assessed. Analysis was performed using SPSS version 19.0 RESULTS: Group I consisted of 84 patients. A comparable sample was assigned to group C (n=80). The average phone call lasted 18 minutes (range 7 to 45 minutes). After two years there was a significant reduction of BP values for group I (t = 0: Systolic = 146.8±2.3 Diastolic = 90.2±4.2, t = 24 months Systolic = 138.4±4.6 Diastolic = 86.9±3.8) (P<0.001). From baseline to two years, BMQ analysis showed an adherence improvement in group I (t = 0 Necessity Score = 15.6±3.5, concern Score = 14.9±2.9, t = 24 Necessity Score = 22.4±2.4 and Concern Score = 10±2.2). Group C did not show any statistically significant results. CONCLUSIONS: These findings suggest that telephone counseling can significantly improve blood pressure control. Our data show also that interventions run by allied health professionals (i.e. other than the prescriber/doctor), improve adherence to medicines and promote hypertension-related health behaviors.