Lyme borreliosis is a worldwide tick-borne zoonosis caused by infection with Borrelia burgdorferi, a spirochete. Erythema chronicum migrans (ECM) is the most common and most specific clinical sign of Lyme borreliosis, and it is a defining criterion for Lyme disease in North America and Europe.1,2 Most patients with ECM do not exhibit any seroreactivity against B burgdorferi.3 Diagnosis relies solely on the clinical recognition of ECM. Therefore, physicians must be able to identify ECM correctly and to differentiate it from other similar erythematous dermatoses. The unique aim of the present study was to evaluate the ability of general practitioners (GPs) and dermatologists to identify ECM in Strasbourg, a city in the eastern part of France and a region in which Lyme borreliosis is highly endemic.4