Bladder irrigation with povidone-iodine in the prevention of urinary-tract infections after single or intermittent urethral catheterisation was investigated in a controlled study. In the control group (36 patients) the catheter was removed after urethral catheterisation and emptying of the bladder, and in the trial group (42 patients) 50 ml povidone-iodine 2% was instilled and allowed to drain immediately before removal of the catheter. The incidence of bacteriuria was 28% in the control group and 4% in the povidone-iodine group. After the introduction of bladder irrigation with povidone-iodine in the orthopaedic department of Leiden University Hospital the incidence of hospital-acquired bacteriuria fell from 6.9% to 3.7%.