Type II NKT cells have been reported to participate in immune regulation of many diseases including autoimmune diseases and cancer. However, their characteristics have not been well understood.  Sulfatide has been shown to be recognized by a fraction of type II NKT cells, and in vivo administration suppresses immune responses.  In this study, we characterized sulfatide-reactive type II NKT cells in liver.  Consistent with previous reports, sulfatide-loaded CD1d-tetramers stained approximately 1-2% of liver mononuclear cells, and the tetramer reactive cells had intermediate levels of TCRβ expression. All of them expressed a very low level of CD4. They were mostly negative for NK1.1. Unexpectedly all sulfatide-reactive type II NKT cells expressed myeloid markers CD11b and F4/80 although they were negative for Ly6C.  Morphological study of sorted sulfatide-reactive type II NKT cells indicated that they appear to be true lymphocytes with slightly larger cytoplasm with azurophilic granules. Ex vivo staining did not detect production of either IL-4 or IFN-γ in the cells from naïve mice.  Also, to our great surprise, they could not be stained with anti-CD3, although sorted cells exhibited very low expression of CD3ε and CD3ζ by PCR and also stained independently with multiple anti-Vβ antibodies.  Consistently, sulfatide-reactive type II NKT cells showed increased Ki67 expression indicative of proliferation  upon in vivo administration of sulfatide. The data suggested that liver sulfatide-reactive type II NKT cells are significantly different from type I NKT cells as well as other non-sulfatide-reactive type II NKT cells.