Active immunisation with rubella vaccine has not been commonly associated with neurological complications. We report the case of a 23-year-old woman who developed a mild, distal demyelinating neuropathy after immunisation with the live attenuated RA 27/3 rubella strain. Post-immunisation immunologic studies carried over 24 months showed the presence of antibodies to the RV proteins, particularly to the capsid antigen, and to the myelin basic protein (MBP). A similarity between a C antigen motif and a sequence of the MBP was found by computer analysis. The cross-reactivity was confirmed by immunising mice with a synthetic peptide derived from the MBP, which developed a strong humoral response to RV and MBP. This finding raises the possibility that a virus-induced immune response could lead to an autoaggressive reaction responsible for demyelination.