In this thesis, structural, electrical and magnetic properties of polycrystalline bulk and thin film samples of La 0.85 Sr 0.15 MnO 3 (LSMO) and La 0.85 Ca 0.15 MnO 3 (LCMO) manganites have been studied. The LSMO powder sample was prepared by sol-gel method and then sintered at 1350 ? C. X-ray diffraction pattern shows that the crystal structure of LSMO sample is a mixture of orthorhombic (space group Pnma) and rhombohedral (space group R-3C) phases. Magnetic properties of LSMO bulk sample was studied by ac magnetic susceptibility. The results showed that the paramagnetic-ferromagnetic transition is occurred at about 254 K. The thin films of La 0.85 Sr 0.15 MnO 3 and La 0.85 Ca 0.15 MnO 3 manganites were deposited on LaAlO 3 (LAO) substrate using the pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) patterns showed that the thin films are c-axis oriented on LAO substrate. Electrical properties of the polycrystalline balk and thin film samples of LSMO and LCMO manganites were studied by measuring the electrical resistance of the samples in the absence and in the presence of magnetic field of 10kOe. It was observed that when temperature decreases below room temperature, the samples show a semiconducting behavior. Then, a metal-insulator transition appears. With a further reduction of temperature, the semiconducting state again appears. The electrical resistance of the samples decreases in presence of magnetic field which is called magnetoresistance (MR). The main goal of this thesis was to investigate the anisotropic magnetoresistance (AMR). AMR is defined as the dependence of resistivity on the angle between the magnetic field and electrical current. The results showed that, in the bulk and thin film samples, the parallel resistivity ( : magnetic field parallel to electrical current) is less than the vertical resistivity ( : magnetic field vertical to electrical current). Moreover, the results show that the thin film of La 0.85 Ca 0.15 MnO 3 exhibit larger AMR, relative to the thin film of La 0.85 Sr 0.15 MnO 3 . This is most likely due to the larger lattice mismatch of LCMO film / LAO substrate, relative to LSMO/LAO.