Lyme disease is a multisystem illness caused by Borrelia burgdorferi, a spirochete transmitted by certain species of Ixodes ticks. Approximately 30,000 confirmed and probable cases of Lyme disease were reported in the United States in 2012, primarily from high-incidence states in the Northeast (Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont) and upper Midwest (Minnesota and Wisconsin). Common manifestations include cutaneous, neurologic, and rheumatologic signs and symptoms. Symptomatic infection of the heart is rare in recognized Lyme disease cases and usually resolves promptly with appropriate antibiotic therapy. Nonetheless, cardiac involvement occasionally can cause life-threatening cardiac conduction abnormalities. During November 2012-July 2013, one woman and two men (ranging in age from 26 to 38 years) from high-incidence Lyme disease states experienced sudden cardiac death and, on postmortem examination, were found to have evidence of Lyme carditis. The three deaths were investigated by the Connecticut Department of Public Health, Massachusetts Department of Public Health, New Hampshire Department of Public Health, New York State Department of Health, and CDC. Donated corneas from two decedents had been transplanted to three recipients before the diagnosis of Lyme disease was established, but no evidence of disease transmission was found. Although death from Lyme carditis is rare, it should be considered in cases of sudden cardiac death in patients from high-incidence Lyme disease regions. Reducing exposure to ticks is the best method for preventing Lyme disease and other tickborne infections.