In this thesis, we studied the structural and electrical properties of the bulk and thin films of La 0.85 Ca 0.15 MnO 3 (LCMO) manganite. Our main aim is the study of the magnetoresistance (MR) and anisotropic magnetoresistance (AMR) (the dependence of resistance on the angle between magnetic field and electrical current) in this manganite. The bulk samples were prepared by sol- gel method and then sintered at 1150 and 1350 . Then we measured the temperature dependence of resistance of the bulk samples in the range of 100 – 300 K by four probe method. The results showed that, at low temperatures, the sample sintered at 1150 is in insulator ferromagnetic phase but the sample sintered at 1350 is in metal ferromagnetic phase. Moreover, the magnitude of MR is higher in sample 1350 . The sample sintered at 1150 shows low field magnetoresistance (LFMR). For both samples, the maximum of AMR occurs near the metal-insulator transition temperature. However, with increasing the sintering temperature, the AMR peak becomes sharper. We attributed the effect of sintering temperature on the electrical properties to the role of grain boundaries. Thin films of LCMO were deposited on SrTiO 3 (STO) and LaAlO 3 (LAO) substrates by pulsed laser deposition (PLD) technique in two different thicknesses (70 and 240 nm). The XRD results showed that the films are epitaxial. Then we investigated the temperature dependence of MR and AMR of the films in the temperature range of 100 – 300 K and in the magnetic field range of 0 - 10 kOe. The results showed that, with decreasing the thickness of the films grown on LAO, the magnitude of AMR increases about three times; however, for the films grown on STO, the magnitude of AMR does not change with thickness. It has been discussed that the larger AMR of the films on LAO originates from the higher lattice mismatch (higher strain) between the film and substrate.