Abstract We investigated the anisotropic magnetoresistance (AMR) effects in polycrystalline La_0.67(Ca_1−x Sr _x )_0.33MnO₃. An anomalously large AMR of 19.1% was observed near the metal–insulator transition temperature (T _MI) in polycrystalline La_0.67Ca_0.33MnO₃, but slight Sr doping could significantly depress the anomalous AMR around T _MI. By studying the temperature, magnetic field, current direction dependence of AMR and the phase transition process, it was suggested that the anisotropic spin-polarized transport and the demagnetization effect together with the metamagnetic transition around T _MI play important roles in the anomalous AMR effects in polycrystalline perovskite manganites.