Significance Lipoprotein lipase (LPL) plays a central role in plasma lipid metabolism, hydrolyzing the triglycerides in lipoproteins and releasing fatty acid nutrients for vital tissues. LPL is synthesized by adipocytes and myocytes and secreted into the interstitial spaces, whereupon it is captured by an endothelial cell protein, GPIHBP1, and transported to its site of action within the capillary lumen. For decades, LPL has been assumed to be a homodimer, with dimerization thought to be required for both secretion and catalytic activity. In the present study, we revisited the notion that LPL is a homodimer. Our findings indicate that LPL and GPIHBP1-bound LPL are active in a monomeric state.