Background The use of hormone replacement therapy (HRT) is prevalent in the age group invited to routine breast cancer screening in many countries. Previous publications have reported reduced sensitivity and specificity of mammographic breast cancer screening associated with current use of HRT. Objectives To review the epidemiological evidence for the relation between use of HRT and the risk of having breast cancer diagnosed between screens (interval breast cancer—sensitivity) and being recalled for assessment after initial mammography with no diagnosis of breast cancer at that screen (false positive recall—specificity). Methods Overview of published literature. Results Eight studies were identified, providing a total of 367 interval cancers and 8878 cases of false positive recall, in women of 50 and over. Overall, the studies showed an increased risk of interval cancer and false positive recall in current users of HRT compared with non-users. Only one study accounted for the essential confounding factors of age and menopause. Furthermore, information on duration and recency of HRT use was not available for most studies. Conclusions Studies to date indicate that women using HRT are more likely to experience reduced sensitivity and specificity of breast cancer screening, compared with women not using HRT. However, because results have not been adjusted for crucial confounding factors, the magnitude of these effects is uncertain.