If a factor could be identified which delayed the onset of cataract by 10 years, the number of annual cataract operations worldwide has been estimated to decrease by 45%. A case-control study compared alcohol consumption in 78 patients attending for routine cataract surgery in South East London with data from a large population-based survey. Male cataract patients had a significantly greater risk of being harmful drinkers (odds ratio = 8, p = 0.007) than the controls. The harmful male drinkers were significantly younger than the non-drinkers with cataract (mean difference 15 years, p < 0.007). Female cataract patients were not more likely to be excessive drinkers than controls. The female drinkers with cataract were of a similar age to the non-drinking female patients with cataract. Haematological and biochemical indices of alcohol toxicity indicated five patients who were likely to be harmful drinkers, but who had denied this on direct questioning. Seven (26%) of the male patients had a low serum 25 hydroxycholecalciferol although the levels were normal in the female patients. These results support the view that excess alcohol consumption is related to cataract formation and suggest that alcohol causes premature cataract formation in male, but not female patients. Alcohol consumption is amenable to intervention and suggests that such intervention could have a significant impact on the need for cataract surgery.