Aggregation behaviors of egg-lecithin vesicles were investigated, The crowded vesicle solution exhibited an irregular aggregation style in the presence of FeCl3, The process was composed of an induction period (2-5 days) and a sedimentation process (similar to 12 h), The vesicles were stabilized by the positively charged species such as [(H2O)(4)Fe(OH)(2) Fe(H2O)(4)](4+) in the induction periods. However, after the stationary state, the vesicles began to coagulate due to the transformation of the iron species into the inactive one. The existence of such time-lag for the aggregation to occur was mainly induced by the transient nature of iron(III) in the aqueous solution.