Severe hypertriglyceridemia is an uncommon pathological finding in pregnant women if there is no prior history of hyperlipidemia. A partial reduction in lipoprotein lipase (LPL) activity due to a mutation in the LPL gene, is often an associating factor. Here we report a novel LPL gene mutation (Glu421Lys), in a previously healthy primigravid woman who died from hypertriglyceridemia-induced pancreatitis during the last trimester of pregnancy. The patient was heterozygous for this mutation which a charge inversion in the C-terminal domain of LPL resulting in a moderate reduction in catalytic activity, both in vivo and in vitro. These data support the role of partial LPL deficiency in the pathogenesis of severe gestational hypertriglyceridemia.