The crystallization of TiO2 in monolithic SiO2-TiO2 (SiO2>TiO2) gels by annealing has been investigated. The temperatures of the crystallization of TiO2 to anatase and anatase-to-rutile phase transition were considerably raised with the addition of SiO2. It is supposed that the anatase-torutile phase transition is primarily controlled by the grain size of the crystals. TiO2(B), one of the TiO2 polymorphs, was formed as one of the first crystalline phase in SiO2-TiO2 gels at 800-900°C. Transmission electron microscope observations revealed that TiO2(B) nanocrystallites with a size of 5-10 nm were dispersed in amorphous SiO2 matrix. TiO2(B) nanocrystallites did not grow larger but transformed to anatase at higher temperatures. It is supposed that the nucleation and stability of TiO2(B) are enhanced with the presence of surrounding SiO2, presumably by a low interfacial energy.