The present study was carried out to investigate the effect of gold (Au) injection on copper (Cu) and two types of ceruloplasmin (Cp), total Cp (ID1) and active Cp (ID2), metallothionein (MT) in the serum, kidney and liver, and 8-hydroxydeoxyguanosine (8-OHdG) in the rat kidney. The Cu contents in sera and kidneys of Au-injected rats were 1.7 and 5.5 times higher than those in sera and kidneys of control rats, respectively. The most of Cu in the sera of the control rats or Au-injected rats were observed in the Cp fractions from a Sephacryl S-200 column. The Cu concentration in the Cp fractions was increased by Au injection. Significant increases of ID1 and ID2 were found in the sera of the control rats and Au-injected rats, while there was no significant difference in those concentrations of livers or kidneys between the control rats and Au-injected rats. Our results indicated that the most of Cp existed as active ID1. The immunoreactivity of 8-OHdG was located in the cortex of the Au-injected rat. These results indicated that the oxidative DNA damage occurred in the renal cortex of the Au-injected rat and the localization of DNA damage did not coincide with that of Cu-MT. These findings suggest that the oxidative DNA damage in the kidneys of rats injected with Au is associated with Cu except Cu-MT.