Objective: Severe hypertriglyceridemia (HTG) (i.e., plasma triglycerides [TGs] >1,000 mg/dL) in children is a rare but pernicious and understudied condition. Our objective was to evaluate the etiology, characteristics, and sequelae of severe pediatric HTG. Methods: This was a retrospective electronic medical record review of pediatric patients with severe HTG at a tertiary referral Childrens hospital over a 17-year period. Results: There were a total of 124 patients with severe HTG. The etiology varied: hemato-oncologic (n = 48), diabetes and insulin resistancerelated (n = 46), total parenteral nutrition (TPN)-related (n = 6), renal (n = 12), and miscellaneous (n = 12). There was considerable variability in the number of days for the plasma TGs to decrease to <1,000 mg/dL (147.7 ± 567.3 days) and to further decrease to <500 mg/dL (136.84 ± 230.9 days). Patients with diabetes required the longest time to improve their plasma TGs (165.8 ± 305.7 days) compared to other groups. There were 11 cases of pancreatitis, comorbid with diabetes (n = 5), hemato-oncologic conditions (n = 3), and TPN (n = 3). Sixty-seven patients (54%) had persistent HTG. Conclusion: Severe HTG in pediatrics is commonly due to secondary causes. Patients with diabetes tend to have a longer course of dyslipidemia. A substantial number of patients had persistent dyslipidemia, indicating underlying genetic susceptibility to HTG that is phenotypically expressed consequent to a secondary metabolic insult. (Endocr Pract. 2018;24:789-795)