Cataract is known to be more common in India than it is in the industrialised world, but there is little evidence to show whether people emigrating from India will continue to have a high incidence of the disease. Data have been collected from the outpatient clinics of a hospital in Leicester, England, that suggest that for people aged over 45 the demand incidence of cataract is more than five times higher in people of Indian descent than it is in the indigenous population. As well as measuring the demand incidence of cataract in Leicester's two main racial groups the data are used to investigate other risk factors. For both communities the demand incidence of cataract is significantly higher in women than in men, and it is significantly higher in people of Indian descent who emigrated directly from India than in those who emigrated from East Africa. Religious subgroups within the immigrant community also show small differences in their demand incidence. The possibility that these differences are linked to diet is considered.