The effect of TiO2/SiO2, addition on the grain growth of alumina was reinvestigated. TiO2 promoted the grain growth, but there was no abnormal grain growth. However, codoping of TiO2 and SiO2 resulted in a duplex microstructure consisting of large platelike grains, similar to 800 mum long and similar to 100 mum thick, and fine matrix grains, The observed anisotropic abnormal grain growth was explained in terms of liquid formation during heat treatment.