The channel capacity of Gaussian noise environment was solved by Shannon in 1949. it provides an upper bound of maximum transmission rate in a given Gaussian noise environment. In this paper the channel capacity in a Rayleigh fading environment has been derived. The result shows that the channel capacity in a Rayleigh fading environment is always lower than that in a Gaussian noise environment. When operating a digital transmission in a mobile radio environment that has Rayleigh fading statistics, it is very important to know what the degradations are in channel capacity due to Rayleigh fading, and also to what degree the diversity schemes can bring the channel capacity up in a Rayleigh fading environment. The curves are generated to show the degradation of channel capacity in a Rayleigh fading environment and its improvement by diversity schemes. © 1990 IEEE