A 7-year-old boy who presented with cyanosis and exercise intolerance was diagnosed with pulmonary arteriovenous malformations (PAVMs) secondary to a congenital superior-mesenteric-vein-to-left-renal-vein (SMV-LRV) shunt. Resolution of the PAVMs (confirmed by chest computed tomography [CT]) occurred after embolization of this shunt. Although the pathogenesis of his PAVM is not well known, this case demonstrated a close relationship between a congenital SMV-LRV shunt and the development of PAVM.