Factor V Leiden is a well-recognized etiology of venous thrombosis, but reports 
of stroke in patients with this mutation are few. Marijuana smoking has rarely 
been associated with thrombosis of cerebral and renal arteries and may be due to 
a direct toxic effect on the endothelium. Reported here is the case of a 
previously healthy young man who smoked marijuana on a daily basis and had an 
occipital lobe stroke; he was found to be heterozygous for factor V Leiden. This 
case suggests that marijuana smoking may increase the risk of arterial 
thrombosis in otherwise healthy individuals who are heterozygous for factor V 
Leiden.