The Northwestern Andean montane forests (NT0145) is an ecoregion on the Andes mountains in the west of Colombia and Ecuador.

Both flora and fauna are highly diverse due to effect of ice ages when the warmer climate zones were separated and the cooler ones combined, and interglacial periods when the reverse occurred.

[3] The ecoregion covers the western range of the Andes with a wide band of elevations including isolated peaks and massifs at the upper levels.

[5] At a sample location at coordinates 2°15′N 77°45′W / 2.25°N 77.75°W / 2.25; -77.75 the Köppen climate classification is Af: equatorial, fully humid.

The epiphyte and understory plant flora is diverse and includes many endemic species of mosses, ferns, aroids, bromeliads, melastomes, and orchids.

Endangered mammals include Baird's tapir (Tapirus bairdii), black-headed spider monkey (Ateles fusciceps), cotton-top tamarin (Saguinus oedipus), equatorial dog-faced bat (Molossops aequatorianus), Geoffroy's spider monkey (Ateles geoffroyi), Hammond's rice rat (Mindomys hammondi) and mountain tapir (Tapirus pinchaque).

[4] Endangered birds include the black-and-chestnut eagle (Spizaetus isidori), black-breasted puffleg (Eriocnemis nigrivestis), chestnut-bellied flowerpiercer (Diglossa gloriosissima), Chocó vireo (Vireo masteri), colorful puffleg (Eriocnemis mirabilis), El Oro parakeet (Pyrrhura orcesi), gold-ringed tanager (Bangsia aureocincta), pale-headed brush finch (Atlapetes pallidiceps), rufous-brown solitaire (Cichlopsis leucogenys), turquoise-throated puffleg (Eriocnemis godini), violet-throated metaltail (Metallura baroni) and yellow-eared parrot (Ognorhynchus icterotis).

[10] Endangered reptiles include the Western Ground Snake (Atractus occidentalis), Tropical Lightbulb Lizard (Riama oculata) and Haensch's Whorltail Iguana (Stenocercus haenschi).

Protected areas include Cayambe Coca, Sangay, Cotopaxi, and Cajas national parks, Dona Juana-Cascabel Volcanic Complex, Farallones de Cali, Las Orquídeas, Munchique, Paramillo, Purace, and Tatamá national nature parks.