The Ti3+ (3d1) based oxide compounds are mostly Mott-Hubbard insulators or barely metallic due to the strong correlation between 3d electrons. With use of distorted perovskite-like structures RTiO3 (R=rare earth) and their R-site substitution with alkaline earth (A=Sr or Ca), we can systematically control the effective electron correlation (U/W) and the band filling of the 3d states. With decrease of the filling or with “hole-doping”, the systems show the insulator-metal transition. Recent progress in experimental investigations on the metal-insulator transition is reviewed.