The objective of this paper is to test the reinfectivity of Toxocara canis larvae in mice that are fed with rat's liver tissue containing larvae in granuloma formed by administration of infective eggs of dog ascarid. A serial experiment was carried out with 10 non-pregnant mice to observe the pattern of granuloma formation and with 10 pregnant mice to establish the intrauterine and the intramammary migrations. Digestion method using Baermann apparatus and histological examination of the tissues of the tissues were applied as required. The results are summarized as follows: 1) Typical granulomas were formed in the liver of white rats. 2) In mice fed with liver tissue of white rats, granulomas were formed more or less rapidly and necrotic change was observed in the center of the granuloma. 3) Some larvae were recovered from the uterus and placenta at the 15th day of pregnancy, but not in the fetus. 4) A few larvae were deteced in mammary gland at the first day after parturition. However, larva disappeared from the unterus after parturition.