It is well-established that multiple sclerosis (MS) in Caucasians is associated with HLA-DR2. A number of studies have indicated that other genes may also influence the susceptibility to MS. Gm allotypes of immunoglobulin (Ig) genes have been reported to be associated with MS several times, but the described associations differ and have not been confirmed. We report here the results of restriction fragment length polymorphisms (RFLP) analysis of the constant gene regions of immunoglobulin gamma (IgG C) 1, 2 and 3 in MS patients and controls, using the restriction enzymes TaqI, PvuII and BstEII. No significant differences were observed, regardless of subgrouping of patients according to clinical disease type or HLA class II phenotype. These results are in contrast with a previous study where a BstEII RFLP was found to differ between MS patients and controls. In conclusion, the hypothesis that constant gene segments of the IgG genes confer susceptibility to MS still lacks convincing experimental support.