A 5 year old boy with serological and clinical evidence of Mycoplasma pneumoniae infection, which was complicated by popliteal artery thrombosis, is described. Intra-arterial urokinase, in conjunction with medical treatment, resulted in clinical recovery and angiographic resolution of the thrombus. The variety of extrapulmonary complications associated with the M pneumoniae infections continues to broaden. Thrombolytic therapies should be considered when similar clinical circumstances arise.