Radial tunnel syndrome and posterior interosseous nerve syndrome is a clinical picture of the radial nerve is affected at the elbow level. Radial tunnel syndrome without causing motor weakness, led to pain and rarely led to sensory impairment while posterior interosseous nerve syndrome can present with hand extensor muscle weakness and without sensory impairment. In this article, we presented a patient, who exposed to forearm trauma and right and third finger extension loss developing and consequently electromyography was determined the posterior interosseous nerve entrapment. The differential diagnosis is emphasized the importance of keep in mind, rarely encountered partial posterior interosseous nevre syndrome radial nerve entrapments. Mehlika PANPALLI ATEŞ1, Hayat GÜVEN1, Sevgi FERİK2, Selim Selçuk ÇOMOĞLU1