The Arunachal macaque Macaca munzala was discovered in 2003 from the high altitudes of western Arunachal Pradesh, and described as a new species in 2005. Vir- tually nothing is yet known of this new macaque spe- cies. In order to generate scientific knowledge on this primate, a field study was conducted to collect infor- mation on its ranging patterns, diet and behaviour. Two multimale multifemale troops were observed for a pe- riod of 112 h in Zemithang valley, Tawang District. The two troops, consisting of 22 and 13 individuals re- spectively, spent on an average, 48% of the observed time in moving and foraging, 36% in sitting and rest- ing, and 16% in social interactions. Foraging alone accounted for 29% of the time-activity budget and was the major activity of the macaques throughout the study. The troops had home ranges of 28 ha and 16 ha respectively, much smaller than those of other ma- caque species studied in similar environments else- where. The macaques ranged largely in the secondary scrub habitat in the study area, where they were ob- served to feed mainly on Elaeagnus parvifolia and Erythrina arborescens. Although fruits of the former species constituted more than 65.8% of the overall diet, this largely frugivorous diet is likely to be seasonal. Our preliminary results suggest the ranging and forag- ing behaviour of the Arunachal macaque to be largely in response to food resource availability. The species also appears to be a typical member of the sinica spe- cies-group of the genus in exhibiting a matrifocal society with tolerant social relationships.