Demyelination induced by mouse hepatitis virus (MHV), strain JHM, is in large part immune mediated, but little is known about the mechanisms involved in this process. Previous results suggest that inducible nitric oxide synthase (NOS2) contributes transiently to MHV-induced demyelination. Herein, we show that equivalent amounts of demyelination were evident at day 12 after MHV infection in mice genetically deficient in NOS2 (NOS2(-/-)) and in C57BL/6 mice. Furthermore, using an established adoptive transfer model and pharmacological inhibitors of NOS2 function, we could demonstrate no effect on MHV-induced demyelination. These results indicate that NOS2 function is not required for demyelination in mice infected with MHV.