  Perturbative Post-Newtonian variations of the standard osculating orbital
elements are obtained by using the two-body equations of motion in the
Parameterized Post-Newtonian theoretical framework. The results obtained are
applied to the Einstein and. Brans - Dicke theories. As a results, the
semi-major axis and eccentricity exhibit periodic variation, but no secular
changes.. The longitude of periastron and mean longitude at epoch experience
both secular and periodic shifts. The Post-Newtonian effects are calculated and
discussed for six extrasolar planets.
