Abstract: Studies in this paper are the effects of target and missile accelerations on terminal miss-distance in differential game optimal guidance for air-to-air missiles. According to the three types of guidance laws obtained, the choice of the weigh ting factors in performance index is discussed and two schemes of time-to-go estimation are given. The simulation shows that missile lateral acceleration, when taken as guidance signal, significantly improves the terminal accuracy, and target acceleration, if it is not large enough when introduced into guidance process, generally has no such big effect.