Complete formation of the most stable lamellar crystal (L(c)2) phase was achieved for dipalmitoylphosphatidylglycerol (DPPG) bilayer membrane in 1.0 mol kg(-1) aqueous NaCl solution. A peculiar stepwise transition was observed from the differential scanning calorimetric measurements when the L(c)2 phase was completely formed. This is probably relevant to the morphological change from rod-like or cylindrical particles to spherical vesicles concomitant with the transition.