In this letter we report large magnetoresistance(MR) in ceramic samples of La1−x Sr x MnO3 (0.1≤x≤0.4) in the temperature range 4.2 K≤T≤350 K in fields up to 6 T. We find that a large negative and isotopic MR exists for the whole composition range studied and the absolute value of resistivity change on application of magnetic field is more for samples with lower x which have higher resistivity. We find that the large MR occurs in the ferromagnetic state only and MR has a close relation with the magnetizationM.