Vesicles composed of N-[3-(dimethylamino)propyl]-octadecanamide (DMAPODA) stearic acid (SA) were prepared through melting and stirring after hydrating HEPES buffer (10mM, pH 7.4). On micrographs, DMAPODA/SA molar of 2:3, 3:2, 1:2, and 2:1 led to the formation of multilamellar vesicles. the degree of vesicle formation and the size of vesicles decreased as the deviated from 1:1. The mean size after sonication was 529 to 2318 nm, depending on the molar ratio of DMAPODA/SA. The Zeta potential of vesicles of 2:1, 3:2 1:1 were greater than +25mV at physiological pH, and thus they are expected show their colloidal stability at the same pH. In calorimetric study, the vesicles of 3:2 prepared in HEPES buffer, and the vesicles of 1:1 prepared either in the buffer in distilled water exhibited endothermic peaks around 51 degrees C to 52 degrees C. The peaks are due to the phase transition of the vesicle membranes, indicating that vesicles were successfully formed even when DMAPODA was present excess. Finally, pH-dependent changes in shape and integrity were investigated a microscope. The disintegration of vesicles was observed in acidic and alkali This is due to that salt bridging was destroyed at those conditions which the vesicles to be unstable. The vesicles might be used as pH-sensitive carriers for therapeutic agents or genes.