Structural, magnetic and magneto-transport properties in the defect Pr 0 . 7 - x x Sr 0 . 3 MnO 3 (0=<x=<0.23) and Pr 0 . 7 Sr 0 . 3 - x x MnO 3 (0=<x=<0.3) perovskite manganite oxides have been investigated. Our samples have been elaborated by the conventional ceramic method. Structural analysis shows that all samples have a perovskite structure with different distortion degrees. X-ray diffraction patterns show that our samples are in a single phase. Strontium-deficient samples crystallized in a rhombohedral structure with R3c space group for 0=<x=<0.2 and in the orthorhombic symmetry with Pbnm space group for x>0.2; while in the praseodymium-deficient samples, the rhombohedral to orthorhombic transition occurs for x>0.1.All the praseodymium-deficient samples exhibit a paramagnetic-ferromagnetic transition when the temperature decreases while the strontium-deficient ones exhibit such transition only for low x values. The magnetic transition temperature shifts to lower values as the strontium deficiency increases and to higher values with the praseodymium-deficient increase. With decreasing temperature, all the praseodymium-deficient samples exhibit a semiconducting-metallic transition, while such transition is observed only for low x values (0=<x=<0.1) in the strontium-deficient ones. At a magnetic applied field of 2T, stoichiometric sample Pr 0 . 7 Sr 0 . 3 MnO 3 exhibits a magnetoresistance (MR) effect of about 60% at 265K. For the strontium-deficient samples (x=0.05 and x=0.1), the MR at a magnetic applied field of 2T is found to be about 90% for Pr 0 . 7 Sr 0 . 2 5 0 . 0 5 MnO 3 and 70% for Pr 0 . 7 Sr 0 . 2 0 . 1 MnO 3 . For the praseodymium-deficient sample (x=0.1), the MR remains constant below T ρ =250K at a value of about 20-25% for H=2T.