We report for the first time on wormlike micelle formation in aqueous mixtures of lysophosphatidylcholine (LPC) and phosphatidylcholine (PC). The viscosity of mixtures of these two phospholipids at total concentrations ≥56 mM showed a marked maximum around LPC molar fraction 0.5 - 0.7, which was ascribed to wormlike micelle formation. The diffusion coefficient of the lecithin, as measured using pulsed-field-gradient stimulated spin echo NMR, suggests that LPC and PC form spherical micelles and vesicle structures, respectively. In mixtures of LPC and PC, individual spherical micelles of LPC and a vesicle structure of PC were found at low temperature. Wormlike micelle formation was manifested in a steep decrease of the diffusion coefficient at temperatures above 55℃. The results indicate that a minimum concentration of both LPC and PC, as well as a molar ratio of LPC to PC close to 0.5-0.6, are prerequisite for thermally induced formation of lecithin wormlike micelles in aqueous solutions. Following formation on heating, the wormlike micelles remained stable on cooling, and no population of smaller spherical micelles could be detected.