OBJECTIVES: An important complication of Benign Prostate Hyperplasia, a bothersome condition of ageing men, is Acute Urinary Retention (AUR). This condition needs acute catheterisation and is a predisposing factor for surgery. Removal of the catheter is only possible in a minority of patients if no drugs are used. Alpha-blockers may increase the success rate of removing the catheter and decrease the need for future surgery. This study assessed the costs of treating patients with AUR with alfuzosin, watchful waiting or immediate prostatectomy in Belgium. METHODS: According to a randomised controlled trial (ALFAUR study) removing the catheter is successful in 47.9% of patients treated with watchful waiting and 61.9% of those treated with 3 days of alfuzosin (cost €0.92 per day). Based on the treatment path and immediate clinical outcome in the ALFAUR study, a medical decision model to compare the costs and health effects of the three possible strategies was built in Excel MS 2000, whereby follow-up results were obtained from epidemiological data. The cost of events was based on a patient chart review (n = 63) in patients with a first episode of AUR and conducted from the health care payer's perspective. The time horizon of the model was 6 months. RESULTS: At 6 months, 32.3% of patients who initially voided successfully were re-hospitalised to undergo a prostatectomy. Six-month cost of patients treated with alfuzosin, watchful waiting and immediate prostatectomy were respectively €4175, €4758, and €6036. These results were robust under a wide range of plausible assumptions. CONCLUSIONS: Based on the current available clinical data, a very small investment (3 units of alfuzosin) can lead to important savings for the public health care payer by treating all patients hospitalised with AUR with alfuzosin. Further research on utilities in these patients is expected to strengthen this conclusion.