A partially fluorinated carboxylate-type anionic gemini surfactant, N,N'-di(3-perfluorohexyl-2-hydroxypropyl)-N,N'-diacetic acid-ethylenediamine (2C(6)(F)edda), formed aggregates with a cagelike structure in an aqueous alkali solution. These aggregates were composed of several bilayer sheets. The TEM micrograph showed that the bilayer sheets were produced from a condensed self-assembly core. The leaflike bilayer sheets-can form folds and link to each other at their edges. The typical size of the spherical cage ranged from ca. 200 to 1500 nm.