In patients with obstructive jaundice due to biliary tract stricture a tissue diagnosis is essential because of the varied treatment options available. Radiological imaging of a biliary stricture may suggest that it is malignant, but only a tissue diagnosis can be conclusive. The difficulty of obtaining biopsy tissue has encouraged the use of cytology in this field. This study prospectively analyzed the diagnostic value of exfoliative bile and brush cytology methods. One hundred consecutive patients with biliary strictures diagnosed at endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography (60 men and 40 women; median age = 71 yr, range = 31 to 91 yr) underwent biliary cytology and were divided into two groups. Group 1 comprised the first 47 patients, who were studied by means of bile cytology alone; and group 2 comprised the subsequent 46 patients, who were studied by means of bile and brush cytology techniques. Seven patients were excluded from analysis because of inadequate follow-up information. A single experienced cytologist examined all samples to determine whether they were neoplastic. Eighty-one patients had malignant strictures and 12 had benign strictures. Combined bile and brush cytology (group 2) was more sensitive than bile cytology alone (group 1) (69% [27 of 39] vs. 33% [16 of 42], p < 0.01). In the patients studied by means of bile and brush cytology methods (group 2), cytologic study of brushings was more sensitive (69% vs. 26%, p < 0.01). No false-positive results were reported in either group (specificity = 100%).(ABSTRACT TRUNCATED AT 250 WORDS)