Lipid membrane dynamics in cell sized vesicles (CSVs) in water is characterized by the solution-state NMR. CSV is successfully prepared by natural swelling method using osmotic effect. Broad H-1 NMR signal and large P-31 NMR chemical shift anisotropy show the slow tumbling of the lipid with the rotational correlation time 0.2-2.8 s in CSV of 10-20 gm-diameters. The H-1-H-1 nuclear Overhauser effect enhancement reveals the proximity between the lipid headgroup and alkyl chains, in which the close distance, similar to 0.4 nm. The proximity is due to the large protrusion of the lipids in the vertical direction to the CSV surface. (C) 2013 Elsevier B.V. All rights reserved.