The magnetization behaviour of amorphous alloys Fe 80-x RE x B 20 (RE = Nd, Sm ) with 0 ≤ x ≤ 16, prepared by melt-spinning technique. The effect of rare earth substitution on the magnetic properties (T c , M 0 , H c …) of amorphous alloy has been investigated. Using Random Magnetic Anisotropy Model (RMA), we have analysed our results and obtained some fundamental parameters.