The A-site deficient ( Sr 1- x RE x )1- y TiO 3 perovskites ( RE = La , Nd and Sm , 0≤ x ≤0.5, y =0, 0.05 and 0.10) were studied using samples prepared by solid-state reaction method. The substitution of Sr by the smaller RE seemed to result in the increased x region of TiO 2 appearance as an impurity phase against the larger y compositions. A slope of the tied line of the lattice parameters a as a function of x was steepened with an increase of y . Electrical conductivity measurements of ( Sr 0.9 RE 0.1)1- y TiO 3 revealed that the samples without cationic deficiency in the A-site were semiconducting whereas the A-site deficient samples showed basically metallic behavior. The absolute value of observed conductivities for all the measured samples were also reduced in the order of the size of RE .