Insulinomas are rare tumors that are usually benign, single and curable by simple surgical excision. They can present problems in diagnosis and localization. Retrospective analysis of patients with insulinoma managed during a 13-year period (1992-2005) at a tertiary-level institution. 31 patients (mean age 38.4 [SD 13.3] years; 16 men) presented with hypoglycemic symptoms for 4.6 (5.5) years. In 22 (71%) patients, the lesion was successfully localized pre-operatively. Of various preoperative localization techniques, CT angiography (5/6; 83%), intra-arterial digital subtraction angiography (11/17; 65%), dual-phase CT (8/14; 57%), and conventional MRI (4/13; 31%) had high rates of successful tumor localization. Intra-operative palpation and ultrasonography also had localization success rates (22/30 [76%], and 11/12 [92%], respectively); each identified one lesion that the other procedure did not localize. Of the 30 patients who underwent surgery, 28 had solitary tumor. Pre-operative investigations to localize insulinoma are helpful despite the availability of intra-operative ultrasound. Dual-phase CT should be the non-invasive investigation of first choice.[Indian J Gastroenterol 2006; 25: 244-247]