In this report we present the first record of Lagothrix flavicauda in montane forests on the eastern side of the Río Huallaga. The record of five groups occurred during primate censuses between the villages of Monopampa and Libertad, along the horseshoe that connects the basins of the ríos Huallaga and Pozuzo. With this record, the known distribution of L. flavicauda is extended to the southeast, up to the boundary with the Región Pasco. Five other primates, among them Lagothrix lagothricha tschudii, occur in the forests there, at elevations above 1900 m above sea level. As in other parts of the Región Huánuco, deforestation is the main threat for the primates and the wildlife in general.