Background. In the Irbesartan in Diabetic Nephropathy Trial (IDNT), treatment with irbesartan demonstrated 23 and 20% reductions in the combined endpoint of doubling of serum creatinine (DSC), end-stage renal disease (ESRD) or death in patients with hypertension, type 2 diabetes and overt nephropathy compared with amlodipine and control, respectively. A simulation model was developed to project long-term cost consequences of the IDNT in Belgium and France. Methods. A Markov model simulated progression from nephropathy to DSC, ESRD and death in patients with hypertension, type 2 diabetes and overt nephropathy. Treatment-specific probabilities were derived from IDNT. Country-specific ESRD-related data were retrieved from published sources. Delay in onset of ESRD, life expectancy and mean lifetime costs were calculated for patients with a baseline age of 59 years. Future costs were discounted at 3% per annum (p.a.), and clinical benefits were discounted at 0 and 3% p.a. Extensive sensitivity analyses were performed. Results. Onset of ESRD was delayed with irbesartan by 1.41 and 1.35 years vs amlodipine and control, respectively. When a 10-year time horizon was considered, delay in ESRD onset led to anticipated improvements in life expectancy of 0.13 years vs amlodipine and 0.26 years vs control. Irbesartan was associated with cost savings of €14 949 and €9205/patient in Belgium, and €20 128 and €13 337 in France, vs amlodipine and control, respectively. The results were robust under a wide range of plausible assumptions. Conclusions. Treating patients with hypertension, type 2 diabetes and overt nephropathy using irbesartan was both cost- and life-saving compared with amlodipine and control.