Apolipoprotein E is an exchangeable apolipoprotein that plays an important role in lipid/lipoprotein metabolism and cardiovascular diseases. Recent evidence indicates that apoE is also critical in several other important biological processes, including Alzheimer's disease, cognitive function, immunoregulation, cell signaling and infectious diseases. Although the X-ray crystal structure of the apoE N-terminal domain was solved in 1991, there is no structure available for the apoE C-terminal domain and full-length apoE. Here we report a complete NMR backbone spectral assignment of lipid-free human apoE.