Mechanical alloying (MA) technique has been used to prepare a series of Cu58Zr42 samples as a function of milling time. This has been done to study the amorphization reaction in this system. Cu58Zr42 has the best X-ray visibility of copmositional short range order (CSRO) of CuxZr1-x system. X-ray diffraction was used to investigate the structural changes during the amorphization reaction. A complete amorphous phase has occurred after 4 h MA time. No diffraction peaks from the intermetallic CuZr phases were observed throughout the amorphization reaction. The crystallization temperature and the activation energy for crystallization of the amorphous CuZr alloy were obtained by differential scanning calorimetry (DSC) measurements.