Different methods of laboratory diagnostics were comparatively analyzed in examining 25 patients at the early infection stage. Sera were measured by using various serological reactions. Specific antibodies were determined by using the reaction of indirect immune-fluorescence (RIIF), the immune-enzyme analysis (IEA) and the complement-binding reaction (CBR) in 83.1%, 54.4% and 12.5% of cases, respectively. Essential differences in sensitivity were detected between the above methods. RIIF was proven to be a reliable and sufficiently sensitive method in the laboratory diagnostics of Lyma's disease. While the use of two methods, i.e. RIIF and IEA, ensures the highest percentage of detection of antibodies to the causative agent of Lyma's disease.