Copper is an essential trace element for sustaining life. However, copper in excess is highly toxic and elevated copper concentrations in cells have been associated with several diseases, including non-Indian childhood cirrhosis (NICC) in man and copper toxicosis in Bedlington terriers. NICC and copper toxicosis in Bedlington terriers are phenotypic very similar to Wilson disease and Indian childhood cirrhosis. Recently, the gene underlying Wilson disease (ATP7B) as well as copper transport genes hCTR1, hCTR2 and ATOX1 have been excluded as candidates for NICC in man and copper toxicosis in Bedlington terriers. Currently, a genome wide screen is being carried out to localize the NICC gene. Isolation of the NICC gene and defining its pathophysiology will significantly expand our insight into copper metabolism in man, which, at present, is largely limited. The availability of a dog mutation with phenotypic similarities to NICC will open up new lines of research for studying the disease if it proves to be homologous to NICC but will still represent an important addition to the list of genes determining copper disease in mammals if it doesn t.