The role of endoscopic ultrasound (EUS) in the detection of pancreatic islet cell tumours is reviewed. Functioning islet cell tumours are frequently small at presentation (90%< 2 cm). Advances in cross-sectional imaging with CT and MRI have resulted in improved detection rates of these small lesions. The sensitivity of EUS in the detection of insulinoma is similar to helical or multislice CT, i.e. between 82 and 94%, while a combination of both techniques is reported to identify 100% of tumours. EUS may be considered a primary diagnostic tool in these patients. EUS has a secondary role in the detection of gastrinomas as over 50% are malignant and 5% extra-pancreatic in position. CT should be used as a first-line investigation. EUS is valuable in problem solving in these patients. EUS has a role in staging large tumours prior to surgery. EUS-guided fine needle aspiration may provide cytological confirmation of the nature of a tumour prior to surgery.