This paper reviews the characteristics of a high pressure ionization gauge originally reported by Schulz and Phelps [Rev. Sci. Instrum.28, 1051 (1957)]. The gauge is available commercially as the Westinghouse WL‐7903. A brief theoretical treatment is given for the linear regime,p≲1 Torr. The gauge sensitivity is derived from known ionization cross sections for a number of atomic and molecular gases, including argon, krypton, and xenon. Also, an improved gauge controller circuit is described. For a given gas the controller normalizes the gauge sensitivity to unity and provides a direct reading of gas pressure on a linear scale. The controller has proved very useful in the operation of a cw flowing‐gas laser in which 0.1 to 300 mTorr pressures occur. In addition, new experimental data are presented for argon, krypton, nitrogen, and air in the ``nonlinear'' range 2–500 Torr.