Black women have lower age-standardized breast cancer incidence rates than White women in the United Kingdom. However, little is known about such differences in risk in separate age groups. Records on female residents of South East England diagnosed with breast cancer between 1998 and 2003 were extracted from the Thames Cancer Registry database. Age-specific incidence rates were calculated for each 5-year age group using 2001 Census population data for White, Black Caribbean and Black African women. Black Caribbean and Black African breast cancer patients were younger than both the White patients and those with no ethnicity recorded. Black Caribbean and Black African women in the population also had a younger age profile than White women. The computed age-specific incidence rates in women aged under 50 were similar in the different ethnic groups, whereas in women aged 50 and over White women had higher rates. The younger age of Black Caribbean and Black African breast cancer patients in South East England reflects the younger age of these populations, rather than an increased risk of disease at younger ages.