Due to multiple-drug resistant bacteria, phage therapy is being revisited. Although most animal experiments focus on therapeutic efficacy, the blood clearance kinetics of phages have not been well described. For further development of an efficient therapeutic strategy, information on phage blood kinetics is important. In this study, time-course concentration changes in peripheral blood of healthy and neutropenic mice were measured using four therapeutic phages (phiMR11, KPP10, phiEF24C, and KEP10). The results showed a two- to three-day rapid phage clearance, which fits a two-compartment model.