Xenopus laevis, a frog commercially traded as a laboratory and pet animal, was first recorded in the wild at four localities in the Kanto plain, central Japan. Frogs found in the Tonegawa River might be a feral population established in the past decade because several X. laevis have been collected intermittently since the late 1990's. It is uncertain, however, whether Xenopus found at three other localities (Hasuike Pond in Fujisawa City, Inbanuma Pond in Shisui Town, and A ditch in Nagara Town) have established feral populations because there are few or no subsequent capture records since the first record at each locality.