OBJECTIVE: Evaluation of the economic impact of hypertension and its correlates. METHODS: Twenty-seven GPs and 9 specialist centers participated in this longitudinal study. Information on lifestyle, SBP, DBP, comorbidities, diagnostic and lab exams, hospitalizations, physicians' visits, drug and medical therapies was collected. We report on healthcare costs (hospitalizations excluded), quantified in the perspective of the Italian National Health Service (NHS), by means of tariffs expressed in Italian Lire 1998, and referred to a three-month period. We used multivariate linear regression to investigate the association between healthcare costs, drug cost (or proper transformations) and the level of SBP and DBP. P<0.05 were considered statistically significant. RESULTS: 416 patients were assessed, 210 women (mean age 63 ± 15) and 206 men (61±12). The mean levels of SBP and DBP were 149 ±11 and 90±9 mmHg for men and 149±15 and 88±9 mmHg for women. The total three months cost of hypertension care was Lit 294.221 for men and Lit.253.938 for women (NS, Mann Whitney U test). Drugs represented the largest part of costs (58%), possibly due to the short time span. We found that new patients tend to be less costly (P=0.006). Patients enrolled by specialists centers (P<0.001); patients with comorbidities (P<0.001); smokers (P=0.002) and previously hospitalized patients were more costly (P<0.001). No influence of age and sex was detected. The health care cost of hypertension was associated with the level of SBP (P=0.007) and DBP (P<0.001). The cost of drug therapy was significantly higher in patients with higher SBP and DBP levels (P<0.001 and P = 0.005 respectively). DISCUSSION: Hypertension is a quite costly disease. Healthcare costs of hypertension and the costs of anti-hypertensive drug therapy are associated with the level both of SBP and DBP. Interventions effective in controlling SBP and DBP are likely to affect costs.