The popliteal artery is the most common site of peripheral aneurysmal formation. Arteriosclerosis, syphilis and mycotic infection are the most common etiological factors while in young adults, the aneurysm is often of the false type and caused by trauma. 1,2 Osteochondroma around the knee joint can give rise to such pathology that was first described by Brailsfords in 1953 3,4 followed by a more detailed account by Paul in the same year. 5 Since that time, approximately 27 cases have been reported in the English literature, including ours. 6-10,16,20-22 Case Report A 23-year-old Saudi male was referred from another hospital with a history of severe pain and swelling in the right lower limb which occurred during jogging. The patient experienced difficulty in walking due to the pain and the decreased movement of the knee, but no pain at rest. There was a family history of hereditary multiple exostoses (HME). Physical examination showed diaphoretic skin, marked swelling of the right posterior lower extremity distal to the mid thigh primarily behind the knee. There was increased warmth and tenderness and palpable popliteal pulse. A thrill was reported early at the referring hospital, but disappeared after arrival at our hospital. All pedal pulses were palpable. The ankle/brachial pressure was 0.8. We recommended medical advice and treatment to the members of the family who were suffering from HME but the family refused. Investigation Plain x-ray showed multiple osteochondroma over the left shoulder and left knee (Figure 1). Computed tomography (CT) and angiogram showed a false aneurysm at the popliteal artery with bony spikes originating from both femurs (Figures 2 and 3). This was performed in the referral hospital. Magnetic resonance imaging (MRI) performed at our hospital confirmed the presence of a large pseudoaneurysm which showed areas of decreased signal, signifying flow and a small area of hematoma seen medially (Figure 4).