The AtacamaMyotisis an endangered and poorly studied bat species, endemic from Peru and Chile. Using mist nets and ultrasonic recordings we release new information on activity patterns and roost use byM. atacamensisin Chile. We also report new records for the species, extending its distribution range to Santiago Metropolitan region. Our results suggest a wide distribution and relative abundance ofM. atacamensisin northern Chile, in addition to remarkable habitat diversity for populations of this species. Bats were active in both natural and anthropogenic habitats. Abandoned mines and buildings in rural villages were the roosts most used by the species. These data provide additional information on the distribution, ecology, and natural history ofM. atacamensisand can be useful in the design of conservation action plans for populations in the country.