Dialkyldithiocarbamates injected into mice 0.5 h prior to alloxan protected dose-dependently against the diabetogenic action of alloxan, and increased blood glucose levels at the time of alloxan injection. Furthermore, they exhibited anti-oxidative properties in vitro such as inhibition of lipid peroxidation, removal of hydrogen peroxide and reduction of the stable free radical, 1, 1-diphenyl-2-picrylhydrazyl (DPPH). These results suggest that dialkyldithiocarbamates protect against the development of alloxan-induced diabetes by the indirect mechanism of producing hyperglycemia at the time of alloxan injection and possibly by their anti-oxidative effects as well.