Pseudoaneurysms of the popliteal artery (PPA) rarely occur in children. In fact, we found only 10 cases reported in the medical literature. We report the case of a 4-year-old boy who presented with a painful palpable mass in the right popliteal fossa. He also had mild, painless right foot-drop and difficulty toe-walking on the same side. The diagnosis of a PPA was based on the findings of triplex ultrasound and computed tomographic-angiography. We attributed the cause of the lesion to blunt trauma, which he had suffered 2 years earlier. Thorough preoperative evaluation excluded the possibility of a self-immune process or a bone tumor in the region. Neurological examination demonstrated a mild, isolated, peripheral mononeuropathy of the right peroneal nerve. Thus, we performed surgical repair using an autologous reversed great saphenous vein graft. The patient had an uneventful postoperative course and his peripheral neuropathy and foot-drop resolved completely within 1 month after surgery. Now, after 3 years of follow-up, the patient has a patent graft and a fully functioning limb. PPAs are rare, especially in children, and trauma is the predominating underlying cause. PPAs should be treated immediately after diagnosis because their complications are associated with high rates of functional impairment and even limb loss.