Leptopelis mackayi, the Mackay's forest treefrog or Mackay's tree frog, is a species of arboreal frog from the family Arthroleptidae. Described in 2006, it is currently known from the Kakamega Forest of western Kenya (its type locality) and from eastern Democratic Republic of Congo; its full range is likely wider, including suitable habitat in the intervening Uganda.
The specific name mackayi honours Alex Duff-MacKay (1939–2003), herpetologist active in Kenya.
Males grow to 361NaN1 and females to 401NaN1 in snout–vent length. The head is slightly wider than the body. The snout is rounded. The tympanum is distinct and round or slightly oval. The fingers and the toes have partial webbing, lateral fringes, and round terminal disks. The dorsum is pale brown with a dark, irregular pattern and fine white spots. There is a white spot under the eye. Males have a white vocal sac.
A Gosner stage 27 tadpole measures 271NaN1 in length, of which the tail makes two thirds.
Leptopelis mackayi is an arboreal species forest species found at elevations of . Specimens have been located in both secondary forests and disturbed environments. One tadpole was identified within a puddle. Egg deposition is probably terrestrial, with the tadpoles wriggling themselves into puddles.
This species is considered "vulnerable" because it is only known from two localities and because its habitat is believed to be declining in quality and quantity. It is present in the Kakamega Forest National Park.