Microcatheter entrapment during Onyx embolization is a serious complication; if the catheter cannot be retrieved, options include leaving it in situ or surgical removal. After Onyx embolization of a tentorial dural arteriovenous fistula, the microcatheter became trapped and fractured when retrieval was attempted. The distal stump was beveled, and the stiff end of a smaller-diameter microwire was inserted into the Onyx-filled lumen, which compressed around the wire to provide firm fixation. A 6-Fr distal access catheter was then advanced coaxially, allowing a snare loop to grasp the trapped tip and facilitate retrieval. The trapped segment was detached and successfully retrieved, leaving only a small distal fragment; no hemorrhage or new catheter-related events occurred. Intraluminal wire extension secured by Onyx, combined with coaxial distal access, is a practical bailout technique for Onyx-entrapped microcatheters.