Pressurized stairwells have been used increasingly in the past few years to provide smoke free escape routes. However, there are no accepted design procedures for these systems. This paper provides a discussion of several of the designs currently in use. In particular, single and multiple inject.ion systems are discussed. A report is made on field tests on 5 pressurized stairwells. The testing is part of a continuous program to evaluate alternate systems, in an attempt to establish design recommendations for the future.