OBJECTIVES: There are classical radiological features for the diagnosis of chronic pancreatitis (CP) on endoscopic retrograde cholangiopancreatography (ERCP), magnetic resonance cholangiopancreatography (MRCP) and computed tomography (CT), however, not all patients exhibit these features despite convincing clinical histories, which may result in diagnostic delay. The aim of this study was to assess the use of endoscopic ultrasound (EUS) in the diagnosis of CP when other imaging modalities had not yielded a diagnosis. METHODS: All patients undergoing pancreatic EUS between January 1996 and December 2004 were identified from the radiology computerised database. Sixteen patients with a clinical diagnosis of CP (10 male, mean age 53 +/-4 years) underwent EUS after normal conventional imaging. RESULTS: Thirteen patients exhibited features of CP unidentified by other modalities, which included duct dilatation (n=8), calcification (n=7); parenchymal change (n=6), irregular undilated ducts (n=2), and pancreatic ductal calculi (n=1) and fine calcification. Of the remaining 3 patients, a diagnosis of sclerosing pancreatitis was made in one, in another, there was a pancreatic duct stricture of uncertain origin which was stented, and in only 1 case was no diagnosis established. CONCLUSIONS: EUS provided additional diagnostic information in 94% of patients in the above series, in particular early CP, when cross-sectional imaging or ERCP had failed to support a diagnosis of CP. EUS should be used as a second line investigation in the face of patients with negative CT and MRCP with convincing clinical diagnoses of CP.