The experimental results of the inverted Lamb dip of a 633‐nm He‐Ne laser with a neon discharge‐absorption cell are compared with the theoretical results in detail. The rate equation approximation which is valid for a wide range of the saturation depth is used as a theoretical basis. After the fitting procedure, the theoretical curve approximates the experimental result in good agreement. The parameters, such as the central frequency, the homogeneous linewidth, and the saturation parameter are determined from the best‐fit condition. The 12±3‐MHz/Torr pressure shift of the central frequency of the laser transition is obtained for 5.3:1 He‐Ne mixture.