Puku stand about 80 centimetres at the shoulder and weigh from 70 to 80 kilograms. Puku are sandy brown in colour, the underbelly is a slightly lighter brown. Their coat is rougher than the similar-sized Southern Reedbuck, Lechwe or Impala, or the smaller Oribi. Males have around 50 centimetre long ridge structured horns which are very vaguely lyre-shaped.
Puku are found almost exclusively in marshy grassland and dambos where they eat grass. Puku are crepuscular, they are active in the early morning and late afternoon. When scared, Puku repeat a shrill whistle sound. Females gather in herds of up to twenty individuals. During the rainy season many herds will come together for added safety, typically reaching around fifty females. Males hold territories and attempt to persuade herds of females to stay within their territories for as long as possible.