OBJECTIVE: To determine whether antibacterial effects of cranberry extract will reduce or eliminate bacteriuria and pyuria in persons with spinal cord injury (SCI). DESIGN: Randomized, double-blind, placebo-controlled study. PARTICIPANTS: Participants were people with SCI residing in the community who were 1 year or longer postinjury with neurogenic bladder managed by intermittent catheterization or external collection device and a baseline urine culture demonstrating at least 10(5) colonies per milliliter of bacteria. METHODS: Each participant ingested 2 g of concentrated cranberry juice or placebo in capsule form daily for 6 months. Baseline urinalysis and cultures were performed at the time of the initial clinic visit and monthly for 6 months. Microbiologic data were evaluated using analysis of variance with repeated measures. RESULTS: Twenty-six persons received cranberry extract and 22 persons received placebo. There were no differences or trends detected between participants and controls with respect to number of urine specimens with bacterial counts of at least 10(4) colonies per milliliter, types and numbers of different bacterial species, numbers of urinary leukocytes, urinary pH, or episodes of symptomatic urinary tract infection. CONCLUSION: Cranberry extract taken in capsule form did not reduce bacteriuria and pyuria in persons with SCI and cannot be recommended as a means to treat these conditions.