We have investigated the hysteretic electro-optic behavior of super-twisted nematic (STN) displays with the twist angles larger than 270 degrees. A pair of Lagrange’s equations based on the continuum theory were solved numerically. The Gibbs energy and elastic energy of the nematic liquid crystal medium under the influence of external electric field were calculated. The director configurations at an applied field may be significantly different depending on the initial conditions. The elastic energy of the liquid crystal medium is used to describe its bistability. The total Gibbs energy, which represents the stability of the system, is discussed with each bistable state. The effects of cell twist angle, elastic constants, thickness to pitch ratio, dielectric parameter, and surface pretilt angle are presented.