With regards to application to sensors, the La0.7Sr0.3MnO3 polycrystalline films are well-suited systems, owing to its relatively high Curie temperature (about 360 K) and the saturating behaviour of the magnetoresistance due to the grain-boundary transport contribution. Therefore, we have grown La0.7Sr0.3MnO3 polycrystalline thin films by pulsed laser deposition (PLD) with a KrF laser at two different O-2 pressures (0.3 and 0.05 mbar). The targets were produced by ceramic and sol-gel method and the substrates used were Si with an amorphous SiO2 buffer layer and polycrystalline Al2O3. The films were heated during the deposition at about 500 degrees C and were crystalline without need of fin-ther annealing. Microstructure study was performed by X-ray diffraction and scanning electron microscopy. Magnetotransport measurements have been performed at room temperature, obtaining MR of about 4 % at 1 T and at room temperature. Thus, it seems fairly adequate for obtaining magnetic sensors based in manganite oxides.