Hypertriglyceridemia (HTG) is a problem that occurs frequently in clinical practice. Its prevalence in adults is close to 10% and it varies between regions. The spectrum ranges from a disposition that results in HTG only in the presence of considerable overweight and/or excessive alcohol consumption to very rare serious mutations that can lead to severe HTG in childhood, even in the absence of additional factors such as familial chylomicronemia syndrome (FCS). This is a rare autosomal recessive disorder of chylomicron metabolism that causes a severe elevation in triglyceride levels (>10 mmol/885 mg/dL). This condition is associated with a significant risk of recurrent acute pancreatitis. Because this is a genetic condition, the optimal diagnostic strategy remains the genetic test. In addition, a clinical score for the diagnosis of FCS has been proposed but it needs further validation. Available treatment options to lower triglycerides, such as fibrates or omega-3 fatty acids, are not effective in patients with FCS. Currently, the cornerstone of treatment remains a very low-fat, lifetime diet that reduces chylomicron formation. Finally, apolipoprotein C-3 inhibitors are under development and may eventually be treatment options for these patients. The objective of this article is to carry out a general review of severe HTG, with an emphasis on FCS and based on the most recent available literature.