Rarefied choked flows in parallel-plate channels have been studied using the direct simulation Monte Carlo technique. Calculations are performed for various transitional flows, and results are presented for the computed flowfield quantities, wall pressures and discharge coefficients. Comparisons are made with the available experimental data, and the physical and numerical factors which affect the solutions are discussed. Separate calculations are performed for the "nearly-incompressible" rarefied channel flows in which density variations are small. The calculations of this study indicate that the DSMC simulations are well suited for determining transitional flows from free-molecule limit to laminar flow regime, but become prohibitive for turbulent channel flow simulations with today's computers.