The current status and the limitations faced by available membrane materials used for gas separations are reviewed. One of the biggest challenges that emerges from this survey is the need for materials with enhanced permselectivity with at least equivalent productivity compared to current materials. So called "mixed matrix" materials comprising molecular sieving entities such as zeolites dispersed in conventional polymer materials are possibly attractive solutions to this challenge. These materials ideally offer the excellent transport properties of molecular sieving materials with the processability of polymers, offering a cost effective solution to the need for economical high selectivity membrane materials. The potential impact of mixed matrix materials on the current applications is considered and the status of mixed matrix materials is presented in this paper.