Multiple sclerosis (MS) is an inflammatory disease affecting the central nervous system. The dysregulation of the cytokine network is an important component of its pathogenesis. One of the cytokines produced by activated T-cells is osteopontin (OPN). OPN enhances the production of the pro-inflammatory cytokines, interleukin-12 and interferon-gamma, while reducing interleukin-10 levels. Therefore, OPN is considered a pro-inflammatory cytokine, and could play a key role in MS pathogenesis. The OPN gene contains several common polymorphisms, distributed in two main haplotypes, which may modulate its production or activity. A total of 326 MS patients and 484 healthy controls were typed for 795CT OPN polymorphism. In order to perform a familial study, 51 progenitor pairs were also included. No difference was found in the case-control or family study. This negative finding is inconsistent with a previous haplotype study in an Italian population, where the haplotype associated carried the low-frequency allele in position 795. In a Japanese population, a similar study yielded no association with this polymorphism. In conclusion, our data suggest that the 795 polymorphism does not play an etiological role per se and the haplotype structure may differ from one population to another.