The study evaluates the impact of advances in biliary imaging techniques on the accuracy and rapidity of diagnosis in patients with obstructive jaundice. Two series of patients hospitalized at an interval of 5 years in the same clinic were prospectively analyzed. In both series, the results of ultrasonography (US) and percutaneous transhepatic cholangiography (PTC) were compared with the intraoperative findings. The performances of US in the assessment of ductal dilatation and choledocholithiasis significantly improved during this period. The fine-needle biopsies taken from the solid masses in liver or pancreatic parenchyma under US guidance in the second series of patients contributed to the greater proportion of correct preoperative diagnoses in this group. The number of PTC investigations increased in the second group (p less than 0.001) given the clinicians' confidence in the safety and easy performance of this method. Using both methods, the etiology of biliary obstruction was correctly diagnosed preoperatively in 85.2 per cent of the second series of patients, significantly more frequently than in the first series of patients (62.7 per cent) (p less than 0.05). The mean period in hospital necessary for the diagnosis decreased during the period analyzed from 15.4 +/- 10.8 days to 10.2 +/- 7.8 days (p less than 0.05), a fact with direct impact on the course of disease, and also on the hospital costs.