Abstract: In indoor environments, ultra-wide band signals suffer from dense multipath propagation and severe time dispersion. Rake reception is an important way to boost the performance of ultra-wide band receivers. With the assumption that BPSK modulation is used, the equations used to compute BER performance of Rake receivers in dense multipath channels are derived. The BER performance is related to the multipath channel parameters and the pulse autocorrelation coefficients. With a typical channel model and specific pulse shapes, the computation has been done.