The case of a 79-year old man who was suspected to have an insulinoma is presented. Although clinically and biochemically an insulinoma was the most probable diagnosis there was no supportive radiological evidence. Open surgery and exploration revealed a lesion which was confirmed to be an insulinoma. The patient’s hypoglycaemia improved immediately following surgery. In the Sri Lankan setting where sophisticated imaging procedures are not freely available, open exploration of the pancreas is a good alternative to locate a suspected insulinoma.