Peroneal nerve entrapments at the knee level is the most common mononeuropathy at the lower limb. Superficial trace of the peroneal nerve under the skin and crossing the knee joint facilitate the nerve injuries. Also, strains of the knee joint, tibia and fibula fractures, inversion sprains of the ankle, not properly placed leg plasters, crossing leg for a long time, squatting and staying on the knee can cause the injury. The most significant symptoms are drop foot and numbness at the dorsum of the foot. At the physical examination, we can see the decrease or lost of ankle dorsiflexion and foot eversion. L5 radiculppathy and methabolic sonsorimotor neuropathy should be considered in differential diagnosis. The purpose of this review is to determine the importance of physical examination, differential diangnosis and treatment modalities according to the etiology of the peroneal nerve entrapment.