To determine the factors responsible for therapeutic failures in acute cholangitis, a series of 127 patients was analyzed. There were 64 females and 63 males whose mean age was 57.2 years. Ninety-four (74.0%) of these patients were clinically cured with initial measures, whereas 33 patients (26%) failed initial therapy for an infectious reason. No differences were observed between the two groups in regard to age and gender. However, more patients in the group that failed had a malignant cause for their bile duct obstruction (72.7% vs. 42.6%, p < 0.01) and had a pretreatment positive blood culture (45.5% vs. 13.8%, p < 0.01). Patients who failed had a higher mean total bilirubin level (9.7 mg/dl vs. 5.5 mg/dl, p < 0.005) and more of them had a level greater than 2.2 mg/dl (97% vs. 69.9%, p < 0.001). Also, more bile cultures were initially positive (93.9% vs. 76.6%, p < 0.05) and more organisms were isolated per culture (3.88 vs. 2.86, p < 0.03) in the patients who failed. In addition, more patients failed who had two or more organisms in the bile (33% vs. 8.3%, p < 0.02). Patients in whom Candida, or any panresistant organism was isolated also tended to fail. Multivariant analysis showed that malignancy, bacteremia, bilirubin > or = 2.2 mg/dl, > or = 2 organisms in the bile and a panresistant organism were the best predictors of treatment failure with a serum bilirubin level > or = 2.2 mg/dl being the variable that increases a patient's log-odds ratio of failure the greatest.(ABSTRACT TRUNCATED AT 250 WORDS)