CA 19-9 is a tumour marker which has been used widely in patients with pancreatic: adenocarcinoma. Elevated levels are associated with advanced disease at presentation and disease progression during follow-up, CA19-9 levels may also be elevated in a variety of other malignant and benign conditions, This study examined the significance and implications of elevated CA19-9 levels. An analysis of all CA19-9 measurements performed over a 4 yr period was undertaken and 204 patients with elevated CA19-9 levels were identified, One hundred and thirty patients (63.7 per cent) had malignant conditions and 74 (36.3 per cent) had benign conditions or no definite cause was found. There was a significant correlation between CA19-9 levels and CEA (r = 0.3137; P < 0.001) as well as alkaline phosphatase, ALT, AST, bilirubin, gamma glutamyl transpeptidase and lactate dehydrogenase. CA19-9 levels were significantly lower in patients with benign pathology than those with malignant pathology Similar differences were observed for CEA, CA19-9 levels were in fact highest in patients with pancreatic carcinoma (P < 0.05) while no significant differences were observed for CEA. In conclusion CA19-9 may be elevated in both benign as well as malignant conditions and interpretation of CA19-9 results must be made in light of the clinical condition of the patient.