A general Jones matrix representation for an arbitrary pretilt twisted nematic (TN) cell at any given applied voltage is obtained. A simplified Jones matrix representation for the high pretilt TN cell at the field‐off state is derived from this general Jones matrix representation. The validity of this simplified representation is examined by comparing the optical transmission of a high pretilt angle TN cell, at the field‐off state, as a function of the cell gap thickness obtained from this simplified representation with that obtained by the general representation. The result shows that the simplified Jones matrix representation for a TN cell at the field‐off state works very well even for the pretilt angle as high as 30°. In addition, a property of the average tilt angle of a TN cell is reported.