We report a unique method using transcatheter Onyx embolization in a bleeding due to morphine injection in the gluteal region. A 47-year-old man with a rare blood type presented a painful gluteal hematoma due to iatrogenic injury. A computed tomographic angiography verified bleeding from a suspected branch of the deep femoral artery. Because of the unbearable pain, the hematoma was evacuated by means of computed tomography (CT)-guided puncture and the insertion of a pigtail catheter combined with the injection of a human plasminogen activation agent (t-PA). The initial result was positive. To stop the bleeding, angiographic embolization with Onyx was successfully used. Onyx can be used in small vessel bleedings and might offer the advantage of selective embolization in cases where the access to the bleeding vessel is challenging or time-consuming.