  We present measurements of anisotropic magnetoresistance of
La_{0.75}Sr_{0.25}MnO_3 films deposited on (001) SrTiO_3 substrates, and
develop a model to describe the low temperature AMR in manganites. We measure
an AMR of the order of 10^{-3} for the current I parallel to the [100] axis of
the crystal and vanishing AMR for I//[110], in agreement with the model
predictions.
