We report the lateral diffusion properties of 2,2'-di-O-decyl-3,3'-di-O-(eicosanyl)-bis-(rac-glycero)-1,1'-diphosphoch oline (C(20)BAS) using pulsed-field gradient NMR (PFG-NMR) and fluorescence recovery after photobleaching (FRAP). C(20)BAS membranes display a melting transition at T-m = 15.7 degrees C, as determined by differential scanning calorimetry and P-31 NMR chemical shift anisotropy. The lateral diffusion coefficient of C(20)BAS, as determined by PFG-NMR and FRAP, at 25 degrees C, were DPFG-NMR = 1.9 +/- 0.6 x 10(-8) cm(2)/s and D-FRAP C(20)BAS = 1.2 +/- 0.1 x 10(-8) cm(2)/s, respectively. In comparison, the lateral diffusion coefficient of the monopolar phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), was 1.8 +/-0.9 x 10(-8) and 2.5 +/- 0.9 x 10(-8) cm(2)/s using PFG-NMR and FRAP, respectively.