One in five people over 65 who drink is consuming an "unsafe" level of alcohol, say researchers.
Experts warned that GPs were "less attuned" to drinking problems among elderly people.
Analysis of health records in London found that heavier drinkers tended to be male and relatively affluent.
For older people, the report said, drinking more than the recommended amount carried an additional risk of confusion and falls.
National guidelines advise no more than 14 units of alcohol a week for women and 21 units a week for men.
Researchers used anonymised GP data from 27,991 people aged over 65 living in London.
Of the 9,248 people who reported drinking alcohol, 21% drank more than the safe recommended limits, they report in BMJ Open.
http://www.bbc.co.uk/news/health-34017910