Ceftriaxone is a third generation cephalosporin remarkable for its wide distribution in the biliary tract. The purpose of this study was to determine whether biliary tract pathology, as observed during surgery, had an influence on this distribution. 52 patients about to be operated upon and presenting with a high risk of bile infection received a single 1 or 2 g dose of ceftriaxone administered intravenously over 20 min during the hour that preceded surgery. Samples of blood and of bile from the gallbladder (GB) and the common bile duct (CBD), as well as specimens of the GB wall were taken during the operation. In patients whose GB was normal at laparotomy (apart from stones) ceftriaxone concentrations in bile and GB wall were 10-25 and 2 times respectively higher than in plasma. In patients with a grossly distended but not infected GB (hydrocholecystis) ceftriaxone levels were high in CBD bile but null in GB bile and only one-quarter to one-half of plasma levels in GB wall. In patients with stones in the CBD or inflamed GB wall ceftriaxone levels were high in bile (although lower than in cases with normal GB) and similar to plasma levels in GB wall. When malignant pancreatic lesions were present ceftriaxone concentrations could not be measured in both GB and CBD bile but reached 50% of plasma concentrations in GB wall.(ABSTRACT TRUNCATED AT 250 WORDS)