Abstract: Attenuation due to rain is an important constraint in the designing of the microwave communications nksoperating in Malaysia especially at frequencies above 10 GHz. In recent studies, the ITU-R proposed models forthe prediction of rain attenuation give a good estimation for the microwave propagation loss caused by rain for the temperate regions but it underestimates the rain attenuation prediction for the tropical regions. This paperstudies the rain attenuation prediction models for the design of microwave terrestrial Line-Of-Sight (LOS) systems and research the results of this investigation.