The microwave attenuation due to rainfall in tropical regions has not been very widely studied yet. In Singapore's tropical environment, line-of-sight microwave communication links were set up and have been operated for several years to study the microwave attenuation characteristics due to tropical rainfall. In this paper the experimental results are presented, including the cumulative distributions of rainfall rate, the cumulative distributions of microwave attenuation, the relationship between specific attenuation and rainfall rate, and frequency scaling formulas. The results show that the rainfall rate and the microwave propagation characteristics in Singapore over a 10-month experiment period are out of accord with International Radio Consultative Committee predictions. ¿ 2000 American Geophysical Union