Base station polarization diversity reception in which signals are received by dual polarization (ex. f45" polarization) is discussed. A theoretical analysis is presented on correlation coefficient p between diversity branches, and received signal level decrease L caused by polarization difference at the base and mobile station. The generalized expressions of p and L are then derived. Measurements were also carried out at 900 MHz in an urban area. Consequently, it was found that the p and L values are expressed by three factors, p is lower than 0.6 and L is smaller than 2.5 dB. It is concluded that this polarization diversity reception can be used as an effective diversity reception.