Abstract Adenosine kinase (ADK) deficiency is a very rare inborn error of methionine and adenosine metabolism. It is characterized by developmental delay, hypotonia, epilepsy, facial dysmorphism, failure to thrive, transient liver dysfunction with cholestasis, recurrent hypoglycemia, and cardiac defects. Only 26 cases (16 families) of ADK deficiency have been published since its identification in 2011. Vascular abnormalities in cervical arteries and cerebral stroke have never been reported in this condition. Here, we describe two patients with ADK deficiency and vascular tortuosity leading to stroke in one of them. ADK deficiency is a rare inborn error of methionine metabolism with a complex phenotype that might be associated with cerebrovascular abnormalities and stroke.