Résumé : The performance of 4 screening tests and 10 blot assays for the serologic diagnosis of Lyme borreliosis in a Belgian population was evaluated. A total of 196 sera were tested: 36 Lyme borreliosis at different stages of the disease, 50 healthy blood donors, and 110 representing various clinical circumstances. The DiaSorin Liaison and Euroimmun Anti-Borrelia screening tests were evaluated. The tested blot assays were Virotech Borrelia LINE tests WE222, WE225, and WE224, as well as Mikrogen recomLine Borrelia and Viramed ViraStripe. The specificity of IgG was acceptable for the different assays. For IgM, DiaSorin Liaison Borrelia IgM Quant, Mikrogen recomLine, and Viramed ViraStripe lacked specificity. Interestingly, a higher rate of falsely reactive samples was observed in the group of patients suffering from malaria. Serological diagnosis of Lyme borreliosis remains challenging; assays should be evaluated in the population where they are intended to be used.