A recent survey revealed 237 cases of multiple sclerosis in Wellington, New Zealand, giving an overall prevalence of 69 cases per 100,000. Two hundred and thirty-five were European with one Asian and only one Maori, confirming the rarity of the disease in Maoris. HLA A3, B7 and DR2 antigens were more frequent in multiple sclerosis patients compared with European controls. The same antigens were much less common in the Maori population. The results suggest that Maoris have a low susceptibility to multiple sclerosis despite living in a high risk area, and that genetic susceptibility may be related to the HLA system.