Abstract: Microfilariae (mff) obtained from the peritoneal cavities of infected jirds (Meriones unguiculatus) were injected intravenously into 6 mouse strains: SMMC/B, BALB/cCR, LACA, ICR/JCL, 615 and Kunming strain. The mff in the peripheral blood of the 6 mouse strains in the above sequence were detectable within 1-150, 24-80, 30-60, 3-96, 12-45 and 45-60 days after inoculation of 2 × 105 mff per mouse. The survival period of mff was longer in SMMC/B mice than in mice of the other strains, and the density of mff in blood was also higher in the former than in the latter. Out of 18 SMMC/B mice 13 remained microfilaria-positive on the 60th day after inoculation. The duration and level of microfilaraemia were proportional to the dose of parasites injected Microfilariae disappeared from the peripheral blood of all mice 3 days after injection of 1 ×104 mff, but were still detectable 60 days after injection of 2 × 105 mff. In addition, mff disappeared much faster from the peripheral blood of SMMC/B mice after the second inoculation than after the first one. Although the mff had already disappeared from the peripheral blood of the infected and reinfected mice for about 1 to 2 months, they could still be found in the internal organs, mostly in the small blood vessels of the lungs (about 90%). The mff maintained a nocturnal sub-periodicity in the recipient mice, similar to those observed in the donor jirds, with a peak density hour between 2:28 and 5: 48 a.m.The results show that this mouse model might be a simple and useful system in which various factors controlling the fate of mff can be studied independently.