The invention relates to mRNA therapy for the treatment of hyperlipidemia. mRNAs for use in the invention, when administered in vivo, encode human lipoprotein lipase (LPL), isoforms thereof, functional fragments thereof, and fusion proteins comprising LPL. mRNAs of the invention are preferably encapsulated in lipid nanoparticles (LNPs) to effect efficient delivery to cells and/or tissues in subjects, when administered thereto, mRNA therapies of the invention increase and/or restore deficient levels of LPL expression and/or activity in subjects. mRNA therapies of the invention further decrease levels of triglycerides associated with deficient LPL activity in subjects.