OBJECTIVE: There is evidence of substantial benefit in antihypertensive combination therapy in diabetic patients compared to monotherapy. We evaluated the combination of low dose cilazapril plus low dose doxazosin (Cz+Dx) versus high dose cilazapril (Cz) and versus high dose doxazosin (Dx) in hypertensive diabetic patients in Italy. METHODS: An incremental cost effectiveness analysis was conducted in the societal perspective, considering Health care and indirect costs of treating for 10 years a hypothetical cohort of 1000 male diabetics, aged 50-54 years with levels of systolic blood pressure (SBP) above 160 mmHg, with Cz+Dx vs Cz vs Dx. The effects of considered drugs in lowering blood pressure were derived from the study by Rachmani et al (Nephron 1998). Effectiveness was assessed in terms of morbidity and mortality (life years gained - LYG) and quantified using the UKPDS-36 study (Adler et al, BMJ 2000). Costs are expressed in €2003. We report undiscounted analysis: an analysis conducted using a discount rate of 5% for both costs and effects led to similar results. RESULTS: Cz+Dx therapy showed greater efficacy in reducing SBP compared to both Cz and Dx, leading to lower morbidity and to 231 LYG in the Cz+Dx cohort compared to Cz and Dx alone. Overall cost was lower for the Cz+Dx (€61.7 millions) cohort compared to Cz (€74.1 millions ) and Dx (€73.9 millions). CONCLUSIONS: combination therapy with low dose cilazapril plus low dose doxazosin dominates both high dose cilazapril and high dose doxazosin in hypertensive diabetic patients in Italy, as it is both less costly and more effective.