The incorporation of membrane filtration technology in plant cell suspension culture was to facilitate in situ medium exchange as well as to eliminate possible introduction of contaminant in the process. The study had been carried out in Cyperus aromaticus cell suspension culture, which is known to produce a bioinsecticide known as juvenile hormone III (JH III). The effect of different volume and flow rate of replenishment toward cell biomass and JH III production were studied. The experimental finding indicates that the flow rate of medium replenishment ranging from 1 to 6 ml min-1 did not affect the cellular structure and morphology the cells. Medium replenishment of 75 v/v% through the membrane system leads to higher cell biomass and metabolite production which correlates to a value as high as 64 and 112%, respectively. The reduction in doubling time, extended exponential growth and increment in specific growth rate were also demonstrated. A 50 v/v% medium replenishment with membrane filtration system was identified to be an economical and feasible application for the production of JH III metabolite at a large scale. The results obtained showed the potential of in situ membrane filtration system for the enhancement of cell biomass and metabolite yield in plant cell culture.