A prospective study was performed to quantitate frequency and evaluate risk factors for urinary tract infection (UTI) in 64 catheter-free spinal cord injury (SCI) patients who were visited monthly in their homes for up to 1 year by a public health nurse who performed a physical examination and collected urine for culture and urinalysis. Patients also mailed in urine dip slides weekly. UTI was defined as > or = 100,000 CFU/mL. Of 406 UTIs evaluated, 111 (27%) were asymptomatic, whereas 295 (73%) evidenced some sign or symptom possibly referable to the urinary tract. Fever and chills occurred in 43 (11%) episodes. Incidence of UTI overall was 18.4 episodes per person-year at risk whereas the rate for those associated with fever and chills was 1.82 episodes per person-year at risk. Prevalence of UTI was 57.4%. Pyuria was significantly associated with the occurrence of fever and chills (p < 0.0001), with gram-negative bacterial species being relatively more pyogenic than gram-positive species. Demographic and behavioral factors shown to correlate with risk for UTI by rate ratios and 95% confidence intervals were: black ethnicity, poor personal hygiene, and less-than-daily condom catheter changes. Racial difference was observed independently of the other two variables. Bladder drainage method, age, years since injury, income, education, sex, neurologic level, and administration of prophylactic antibiotics were not correlated with increased risk of UTI. This study provides new data regarding characteristics and frequency of UTI following SCI as well as risk factors that influence its development.