Eleven patients, median age 38 years, with spinal cord lesion (SCL) and urinary tract infection (UTI) caused by multiply resistant bacteria entered an open clinical trial of peroral ciprofloxacin 250 mg b.i.d. for 6 days. P. aeruginosa was the most prevalent bacteria. Ciprofloxacin was clinically effective in all patients who had symptoms of UTI at entry. Bacterial eradication was achieved in 9 out of 11 patients immediately after treatment. At 4 weeks post-treatment 5 patients had relapse of bacteriuria with the initial micro-organism and only 2 had long term eradication. One patient had transient elevation of transaminases, but no other adverse reactions were noted. Pharmacokinetic analysis showed that ciprofloxacin was readily absorbed with a terminal half life of 2.5 hours and considerable nonrenal elimination. The urinary concentration of ciprofloxacin was high during the whole dosing interval. Oral treatment with ciprofloxacin is an alternative to parenteral antibiotics in SCL-patients with urinary tract infection caused by resistant bacteria.