Anionic carbosilane dendrimers of generations 1-3 have been synthesized containing carboxylate G(n)X(C(2)H(4)CO(2)Na)(m) and sulfonate G(n)X(C(2)H(4)SO(3)Na)(m) peripheral groups and derived from two different cores, 1,3,5-(HO)(3)C(6)H(3) (X = O(3)) and Si(C(3)H(5))(4) (X = Si). The peripheral anionic groups make these dendrimers water soluble, despite their highly hydrophobic framework. These dendrimers present a net negative charge in water, which was influenced by the pH of the medium. This characteristic was studied by pH titration. Also molecular modeling calculations have been performed to study differences in an aqueous medium between carboxylate and sulfonate dendrimers of different cores. The results obtained were also compared with those obtained from DOSY NMR experiments and zeta-potential measurements.