A 70-year-old man presented with acute coronary syndrome 3 weeks after plastic stent insertion for hilar biliary stricturing secondary to IgG4-related sclerosing cholangitis (IgG4-SC). Imaging demonstrated haemopericardium due to proximal migration of the plastic biliary stent through the liver capsule and diaphragm into the pericardial sac. The stent was endoscopically removed and a pericardiocentesis was performed. The patient's clinical condition rapidly improved. We illustrate an unusual but potentially serious complication that may arise from migration of a biliary stent and discuss a management strategy.