The White-tailed Hummingbird (Eupherusa poliocerca) is a species of hummingbird endemic to subtropical moist forest in the westernmost portion of the Sierra Madre del Sur in Guerrero and extreme western Oaxaca, Mexico. Its tiny range is threatened by habitat loss.

As is Blue-capped Hummingbird, it is sometimes considered a subspecies of the more widespread Stripe-tailed Hummingbird.