Previously, a structural model, inferred from a crystal structure, was proposed for the micellar aggregates of sodium taurodeoxycholate (NaTDC). This paper described the crystal structure of rubidium taurodeoxycholate (RbTDC), solved both to obtain a model for its micellar aggregates in aqueous solutions and to check whether the micellar structures of NaTDC and RbTDC were similar. In this case, the rubidium salt can be investigated by resorting to the extended X-ray absorption fine structure spectroscopy, which is able to distinguish the nearest-neighbor atoms surrounding the Rb+ ions and allows one to severely test a proposed structural model. Although the NaTDC and RbTDC crystal structures were different, the structural similarity of the NaTDC and RbTDC micellar aggregates was verified by studying their interaction complexes with bilirubin-IXalpha (BR) as a function of pH and BR concentration by circular dichroism measurements, the bile salts being in both submicellar and micellar form. In order to get more enlightening information about the structures of the NaTDC and RbTDC micellar aggregates, fibers were drawn from their aqueous solutions. The X-ray patterns of the two fibers were characteristic helical patterns and showed a very close resemblance. They were interpreted by means of the same unit cell and helical structure. A comparison with the interaction complexes of the sodium deoxycholate, glycocholate, and taurocholate micellar aggregates with BR, previously investigated, was accomplished. The enantioselective complexation of BR to dihydroxy or trihydroxy bile salts was remarkably different and seemed to be mainly dependent on the typical structure of the micellar aggregates.