Dynamics of prey/host and predator/parasitoid interaction has been the main concern of the population ecology during the second half of the 20th century. Many theoretical and experimental studies have been conducted and discussed. The main questions were whether the interaction could be in stable state and whether the parasitoid/predator could regulate the host/prey populations, and if so at what levels. The questions are not yet solved, but some hypotheses have been presented that the prey/predator interaction could be in stable state, when both the predator and prey population are under intraspecific competition so that both populations could be limited at a low levels. This prerequisite, however, could not be easily satisfied in nature and several hypotheses have been discussed up to date. Biological control of pests, which is based on the predator-prey system dynamics, has not always been successful, because we do not understand the systems sufficiently. Thus, most successful cases of the biological control were dependent upon ‘trial and error’. But as the predator-prey system dynamics could be well understood in the future, more systemic control program of biological control could be possible. In this review, we analyzed the studies for biological control of pests in Korea based on 164 cases reported in the last forty years and will consider the future goal of the studies for more reliable control programs.