Without channel state information (CSI) at the receiver, we study receive antenna selection (AS) for multi-antenna systems that employ differential unitary space-time signals. We perform AS only at the receiver and a subset of receive antennas that have the largest received signal power is chosen. Selecting a single antenna at the receiver, it is proved in  that with no CSI at the receiver, the diversity gain with AS is preserved for differential unitary space-time codes with full spatial diversity. In this paper, we generalize the performance analysis to the case of selecting more than one antenna at the receiver. As an immediate consequence of performance analysis, based on the derived diversity gain and coding gain expressions, we develop code design principles for the differential ST codes suitable for maximum-power based AS systems. In particular, for 2 × 2 differential AS systems, we have devised new excellent-performing parametric codes, which outperform known differential codes when AS is employed. Simulation results are presented to validate our analysis and code design.