A method and apparatus for detecting the endpoint in a dry plasma etching system comprising a first electrode (e.g., upper electrode) and a second electrode (e.g., lower electrode) upon which a substrate rests is described. A direct current (DC) voltage is applied between the first electrode and a ring electrode surrounding the second electrode, and the DC current is monitored to determine the endpoint of the etching process. The DC current is affected by the impedance of the plasma, and therefore responds to many variations including, for example, the plasma density, electron/ion flux to exposed surfaces, the electron temperature, etc.