In this study an integrated Newton-Raphson Method (NRM)/Extended Kalman Filter (EKF) Global Positioning System (GPS) based orbit determination for a Low Earth Orbit (LEO) satellite method is presented. The NRM and EKF algorithms are combined to estimate satellite's position and velocity vector components, respectively. Coarse position values computed at NRM preprocessing step are provided as measurement input to EKF algorithm. Orbital motion of LEO satellite is modelled with Keplerian and Newtonian equations taking into consideration the J(2) perturbation effect caused by Earth's oblateness. Compared to traditional methods, utilizing such a preprocessing block (NRM) in filter design considerably reduces the complexity of the filter algorithm.