Significant bacteriuria in women has been found to be associated with increased mortality in community-based studies. We have previously reported a high prevalence of significant bacteriuria with a high recurrence rate in females with primary biliary cirrhosis (PBC), particularly those with late stage disease on liver biopsy. During a 5-year period we prospectively screened for significant bacteriuria in 187 women with primary biliary cirrhosis, (median follow-up of 47 months, range 1-83). Significant bacteriuria was found in 30 (17%) in their first urine (index bacteriuria), 90 (48%) died and 15 (8%) had liver transplants. Cox's proportional hazard models showed that age, serum bilirubin, ascites and cirrhosis were independent prognostic variables. Index bacteriuria added significantly to this model (P = 0.069) being independent from other variables, with an increased relative hazard for death of 1.65 (65% increase in risk of death) compared to non-bacteriuric patients. This effect was due mainly to non-cirrhotic patients with significant bacteriuria as shown by using multiplicative variables for histological stage and significant bacteriuria. An index of recurrent bacteriuria was significantly increased in patients with index bacteriuria (P less than 0.001) and in those who died or underwent transplantation (P less than 0.001). In this study, significant bacteriuria defined a specific sub-group of PBC patients with an increased risk of death.