In the area of the Parque Zoobotânico of Universidade Federal do Acre and in other two areas in Rio Branco, Acre it was devoloped a fieldwork on the migration of Chibui bari (Glossoscolecidae, Oligochaeta) from December 1982 to March 1984. The temperature, the pH, the moisture of the soil and also the monthly precipitation were determined during the period of study. The average of the temperature and the average of the pH of the soil did not present statistical differences between summer and winter. It was verified that this species of earthworm remains active in the winter and that it is in this period that it migrates in both ways: horizontally and vertically. In the summer the animals are in aestivation; they are then approximately 96,0 cm deep in contrast with 42,0 cm, the maximum depth in the period of activity. The migrations we re limited by two factors concerning the soil: its moisture and its availability of providing food.