The authors evaluate the presence of anti-Borrelia burgdorferi antibodies in a group of polysclerotic patients of Eastern Sicily, in order to verify or dismiss a correlation between Borrelia infection and demyelinizing syndrome. 460 samples of serum were examined, of which 60 belonged to patients affected by definite multiple sclerosis; the other 400 were taken from a group of apparently healthy subjects. From the analysis of the data obtained it can be seen that of the 60 polysclerotic subjects examined, 12 equal to 20% were found to be positive for the presence of IgG anti-Borrelia burgdorferi, while in the control group 30 subjects were found to be positive, equal 7.5%.