Prevention of nosocomial urinary tract infections by iontophoresis is addressed. An iontophoretic generator was used to provide microamperage (10 to 400 microA) to vials containing either synthetic urine or supplemented synthetic urine. Bacteria were added to vials, and parameters of growth, bacterial killing, and multiple electrode materials were examined. Escherichia coli and Proteus species were both inhibited and killed at various microamperages and with several electrode types, the most efficient being gold-gold as the anode-cathode combination. Klebsiella pneumoniae in supplemented synthetic urine was least inhibited in growth, and higher microamperage (200 to 400 microA) was most effective in killing the bacteria. Bacterial growth reduction and killing were directly related to increasing microamperage and were inversely related to bacterial concentration.