In this paper, we present case studies of closed chamber testing of low-permeability gas wells immediately after perforating and, report the observations made from the interpretation of these tests. We refer to this type of testing as Perforation Inflow Diagnostic (PID) testing. The procedure for PID testing is: 1) to remove liquids and gases from the wellbore in order to create underbalanced conditions before perforating, and 2) to record surface and/or subsurface pressures in a closed chamber environment continuously throughout the fill up period of the wellbore. The analysis process is to derive a simultaneous gas inflow, rate immediately after perforating using the closed chamber method to determine PID absolute open flow (AOF) potential, in situ gas permeability, skin and reservoir pressure. The assumptions of the diagnostic technique include isothermal and homogeneous reservoir conditions, single phase gas inflow and constant, gas chamber volume. In a majority of the cases where we applied this procedure, we observed an ideal laminar inflow profile. However, a number of 1 pressure responses showed a deviation from this idealized trend suggesting possible inflow of drilling mud filtrates or connate water inflow associated with the gas. In this paper, we present, the well publicized backpressure plot as a diagnostic plot to help T identify liquid inflow when only the simplest of surface recorders', are utilized for field data measurements.