This paper identifies variations in the age and gender characteristics of informal carers in the UK. The paper is based on the Individual Sample of Anonymous Records, a 3% random sample of the 2001 UK Census. The sample size was 1 825 595. Of this sample, 10% were reported to be carers. The analysis shows that informal caregiving is systematically linked with both age and gender. Caregiving increased with age until reaching a peak in the 45-59 age group, in which almost 20% were carers.