In this work we described the results that were obtained using various immunodiagnostic assays for the detection of lyme borreliosis. Sera of the patients that were in acute or chronical phase of the disease were analysed in indirect immunofluorescent, immunoenzyme and immunoblot assays which were prepared and carried out in our laboratory. As a control for the validity of these investigations, we used sera of the healthy people, as well as of the patients suffering of lues or rheumatoid illnesses. Results that we obtained pointed out the factors responsible for the nonspecific reactions in indirect immunofluorescent and immunoenzyme test. The advantage of the immunoblot analysis in detecting lyme borreliosis is described in this work.