Introduction: The departments of Alsace constitute a high-incidence area for Lyme borreliosis (LB) in mainland France. The objectives of the study were to identify and describe cases of three tick-borne diseases, including LB, and to estimate their incidence. Materials and Methods: All patients diagnosed in 2014 and 2015 were reported by participating physicians. Patient characteristics, history of tick bites, and frequented high-risk locations were collected. Reports were classified by a technical committee according to epidemiological case definitions. The incidence of Lyme disease was estimated based on the number of confirmed cases, taking into account physician activity. Results: A total of 388 physicians participated in the study. For Lyme disease, the analysis included 672 cases, of which 4 out of 5 corresponded to a single erythema migrans. Regular visits to at least one high-risk location were reported by 91% of cases. The number of new confirmed cases of erythema migrans was estimated at an average of 2,200 cases per year, representing an average annual incidence rate of 117 cases per 105 inhabitants, which remained stable over the two-year study period. Discussion: This study confirms the high incidence of erythema migrans in the departments of Alsace and its stability during 2014 and 2015. It provides detailed information on the characteristics of the cases. The results suggest that public awareness campaigns should target all outdoor activities.