We report a rare case of femoral nerve palsy secondary to hematoma compression of the iliacus. The patient presented with pain 2 days after performing a double kick in karate. The femoral nerve symptoms (numbness and weakness) did not begin until 3 to 4 days after the initial trauma. Magnetic resonance imaging (MRI) confirmed that there was a hematoma compressing the iliacus (and femoral nerve). This hematoma was subperiosteal, within the iliac fossa. This case is rare because the femoral nerve palsy resolved without surgical intervention, the mechanism of injury, the imaging used to diagnose the iliacus hematoma, and the hematoma was subperiosteal and not within the actual iliacus muscle. A review of the literature regarding femoral nerve palsy secondary to traumatic iliacus hematoma is presented. If the diagnosis of femoral nerve palsy secondary to iliacus hematoma is suspected after history and physical examination, MRI is the imaging study of choice. If MRI does not depict a discreet hematoma mass, nonoperative management should be considered. Electromyography has not been shown to offer information that was not provided by history, physical examination, and other imaging. Surgery should be considered if there is progression of the femoral nerve symptoms, or if MRI depicts a discreet collection of blood impinging on the femoral nerve.