The effects of incorporating an. azo dye moiety as a nonlinear optically active chromophore with benzoyloxyphenyl-substituted mesogens to a cyclic siloxane backbone are reported. The liquid-crystalline (LC) cyclic oligosiloxanes were characterized by H-1 NMR, FT-IR, and UV-Vis spectra. The mesogenic properties of the oligomers were studied by differential thermal analysis, polarizing microscopy, and X-ray diffraction. The results show that all the cyclic oligosiloxanes exhibit the smectic phase except for the cyclic oligosiloxane with azo dye-only substituents, for which the LC state was not evident. The LC cyclic oligosiloxanes, when irradiated at 365nm in chloroform solution, undergo a trans/cis isomerization of the azo dye moiety.