The authors describe the clinical and radiological findings in a case of brainstem arteriovenous malformation (AVM) associated with a hepatic patent ductus venosus (PDV) in a 12-year-old child. The AVM was discovered on magnetic resonance (MR) imaging performed because of slight mental retardation and headache. The malformation was otherwise asymptomatic and no treatment was proposed. An abdominal ultrasonography study performed 1 year later because of hyperammonemia revealed a PDV, which was surgically ligated. One year later, MR images and angiograms showed complete resolution of the brainstem AVM. This report is the first documentation of an association between these two entities in the same patient, and the possible pathophysiological interactions between them are discussed.