The performance of differential pulse position modulation (DPPM) 60 GHz impulse radio (IR) systems with multiple receive antennas is studied in this paper. We derive the capacity and error probability of DPPM 60 GHz IR systems over AWGN channels. These results are then extended to Nakagami-m fading channels. Performance results show that DPPM is superior to pulse position modulation (PPM) in terms of capacity and performance in 60 GHz IR systems. In addition, the capacity and performance can be improved by using multiple receive antennas.