Idiopathic ketotic hypoglycemia (IKH) is an important cause of emergent hypoglycemia among children. We present a case series of 24 patients with IKH in an effort to provide a current clinical description of this disorder. Secondly, we provide a crude lower-bound estimate of the incidence of IKH in an Emergency Department (ED) setting. The charts of 94 non-diabetic patients presenting to an ED during a period of 64 months with a diagnosis of hypoglycemia as identified via ICD-9 codes were reviewed. Eleven patients, accounting for 24.4% of all significant hypoglycemic episodes unrelated to diabetes in children over 6 months of age, were diagnosed with IKH. These patients accounted for 31.4% of hypoglycemic episodes among previously heathy children older than 6 months. A further review of 13 individuals with IKH identified from an endocrinology specialty clinic was also performed. Among all 24 individuals identified with IKH, the mean age of presentation was 30.8 months. We have found IKH to be the most common cause of hypoglycemia among previously healthy ED patients during childhood. In our series, patients with IKH presented initially before 5 years of age with symptomatic hypoglycemia during the morning hours after a moderate fast. These patients were found to have ketonuria with symptoms resolving after glucose administration. Patients with IKH were more likely to be Caucasian, male gender, and have a low body weight.