Abstract: In immunocompetent patients, Lyme carditis is a well-established complication of untreated primary Lyme disease. Whether the presentation and course of Lyme disease differs in immunosuppressed patients has not been well established. There are rare case reports of Lyme disease presenting after solid organ transplantation. We describe a case of Lyme carditis in a patient who received a heart transplant presenting as complete heart block progressing to symptomatic heart failure. The patient required permanent dual-chamber pacemaker placement for cardiac synchronization; however, after treatment with intravenous ceftriaxone, she regained an intrinsic sinus rhythm. Practitioners should maintain a high index of suspicion for Lyme disease when assessing immunosuppressed patients with new-onset heart block. The classic manifestations of primary Lyme disease may be absent as was the case in this patient.