In this report, we present a unique complication of hemodialysis: the hemodialysis access needle was lost into an arteriovenous fistula. The event went unnoticed for several months. The needle eventually migrated into the right ventricle, requiring an operative retrieval. Loss of the needle was likely unrecognized because of the use of a retracting safety cannula that conceals the needle within a sheath after removal. This case highlights a rare and potentially serious complication of hemodialysis access, demonstrates a possible hazard of retracting safety needles, and reviews the management of foreign bodies that have migrated into the heart.