After a brief review on electro-optical (EO) polymers, the recent development of EO dendrimers is summarized. Both single- and multiple-dendron-modified nonlinear optical (NLO) chromophores in the gues-host polymer systems showed a very significant enhancement of poling efficiency (up to a three-fold increase) due to the minimization of intermolecular electrostatic interactions among large dipole moment chromophores through the dendritic effect. Moreover, multiple NLO chromophore building blocks can also be placed into a dendrimer to construct a precise molecular architecture with a predetermined chemical composition. The site-isolation effect, through the encapsulation of NLO moieties with dendrons, can greatly enhance the performance of EO materials. A very large EO coefficient (r(33) = 60 pm/V at 1.55 mum) and high temporal stability (85degreesC for more than 1000 h) were achieved in a NLO dendrimer (see Figure) through the double-end functionalization of a three-dimensional phenyl-tetracyanobutadienyl (Ph-TCBD)-containing NLO chromophore with thermally crosslinkable trifluorovinylether-containing dendrons.