The role of genetic factors in the etiology of multiple sclerosis (MS) has been clearly demonstrated but the loci determining susceptibility to this disease remain largely unidentified. A contribution from several immune system genes has been suggested based on animal models and association/linkage analyses on MS patients and families. With the exception of the findings from the HLA complex, studies on candidate immune system genes have provided controversial results. Here we have performed genetic association and linkage analyses on four chromosomal regions containing immune system genes. A possible role for each of these loci in MS has been previously suggested. In data-sets derived from the Finnish population we found no evidence for contribution of the T-cell receptor beta chain (TCR beta chromosome 7q35), immunoglobulin heavy chain (IGH chromosome 14q32), interferon-gamma (IFN-gamma chromosome 12q14-q15) or interleukin-1 receptor antagonist/interleukin-1 beta (IL-1ra/IL-1 beta chromosome 2q14-q21) loci in the genetic susceptibility to MS.