With a dense covering of spines over the body, the Philippine porcupine (Hystrix pumila) is a highly distinctive rodent. Each spine on the back is flattened, with a rigid tip and a deep groove running along the length. The spines on the underparts are more flexible.

The Philippine porcupine is dark brown to black on the upperparts, paler on the sides, and whitish on the underparts. The short tail bears specialised spines, or ‘quills’, which are hollow near the tip. When several quills are vibrated together they produce a hiss-like rattle.

The Philippine porcupine has very small eyes and ears. Each forefoot has four well-developed digits, each bearing a thick claw, while the hindfeet have five digits. All the feet are covered with coarse bristle-like hairs.