A 64-year-male underwent a liver biopsy based on clinical concern for primary biliary cirrhosis. The biopsy, which yielded normal results, was uneventful, with no immediate postbiopsy complications. A later MRI demonstrated early opacification of the right portal vein on arterial-phase imaging, suggesting communication between the right hepatic artery and the right portal vein. A conservative, watchful management approach was taken. Followup imaging demonstrated a thrombus within the main portal vein, with resulting decreased flow through the fistula. Further followup demonstrated complete occlusion of the main portal vein, with cavernous transformation. The fistula at this time had completely resolved. This an example of spontaneous resolution of an arterioportal shunt secondary to a portal-vein thrombosis. Whether the portal-vein thrombosis was caused by altered flow dynamics within the main portal vein or an unrelated disorder is not certain. The patient had a prior history of deep venous thrombosis, but workup for a hypercoagulable state was negative.