Platymantis biak or Luzon limestone forest frog is a species of frog in the family Ceratobatrachidae. It is endemic to the Philippines, in particular to the Biak-na-Bato National Park on Luzon island. This terrestrial species lives in caves. It prefers low temperatures and is sensitive to temperature changes. Body length is 3.2–4.0 cm for males and 3.7–4.2 cm for females.
