By using more realistic a priori knowledge about the target motion, tracking of maneuvering targets for homing missiles is enhanced. Since certain targets are assumed to execute evasive maneuvers orthogonal to their velocity vector, a new stochastic dynamic target model is proposed where this orthogonality is embedded. Along with this new acceleration dynamic model, the orthogonality is also enforced by the addition of a fictitious auxiliary measurement. The target states are estimated by the modified gain extended Kalman filter (MGEKF), and the angular target maneuver rate is constructed on-line. A guidance law that minimizes a quadratic performance index subject to the assumed stochastic engagement dynamics that includes state dependent noise is derived. This guidance law is determined in closed form where the gains are an explicit function of the estimated target maneuver rate as well as time to go. The numerical simulation for the two-dimensional angle-only measurement case indicates that the proposed target model with the MGEKF leads to remarkable estimation of the target states. Furthermore, the effect on terminal miss distance using this new guidance scheme is given.