Three generations of pyrenyl bis-MPA dendrimers with two different end-groups, acetonide (pyrG) or alcohol (pyr(Gn center dot OH)) (n = 1-3), were synthesized, and the pyrenyl group of the dendritic molecules was encapsulated in the arene ruthenium metallacages, [Ru-6(p-cymene)(6)(OO boolean AND OO)(3)(tpt)(2)](6+) (OO boolean AND OO = 5,8-dioxydo-1,4-naphtaquinonato (donq) [1](6+) and 6,11-dioxydo-5,12-naphtacenedionato (dotq) [2](6+); tpt = 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine). The host guest properties of [guest subset of 1](6+) and [guest subset of 2](6+) were studied in solution by NMR and UV-vis spectroscopic methods, thus allowing the determination of the affinity constants. Moreover, the cytotoxicity of these water-soluble host guest systems and the pyrenyl-dendrimers was evaluated on human ovarian cancer cells.