Transrectal ultrasound-guided core biopsy is a widely used method to diagnose prostate cancer. It is generally considered a safe procedure but the main concern is that signi®cant complications such as infections do occur. To evaluate the effect of a combined two-dosage antibiotic prophylaxis with cipro¯oxacin and metronidazole, a prospective study of 289 patients undergoing core-biopsy of the prostate was performed. Five patients (1.7%) developed urinary tract infection and all did recover without any further complications. The infection rate was signi®cantly lower compared to our historic controls receiving no prophylaxis at all. This prophylactic regime resulted in a low infection rate and it was feasible from the patient perspective. The total cost of antibiotic medication and additional costs due to complications was 18 USD per patient and the cost-effectiveness compared to no prophylactic therapy at all was considered good.