Cyclo(L-aspartyl-L-phenylalanyl)-containing poly(dimethylsiloxane) was synthesized through a simple procedure. This compound had a good organogelation or thickener ability in many organic solvents. X-ray diffraction showed that the gelator forms amorphous, structure due to the presence of poly(dimethylsiloxane). Furthermore, some organogels were thixotropic in that reversible gel-to-sol transition was induced by mechanical stress.