There is a perception that women on oral endocrine treatments for oestrogen receptor-positive breast cancer will be adherent to these medicines, as they are facing a serious life-threatening disease, and the oral endocrine treatments are effective, easy to use and generally well tolerated. This is not in fact the case, and this is the basis of the first half of this review. The second half is of whether the changes/interventions to 'improve' adherence do actually increase adherence to the oral endocrine medicines. The review shows that better outcomes are achieved with good adherence to endocrine treatments in breast cancer. The rates of adherence to endocrine treatments range between 15 and 50%, and are influenced by a large number of factors (e.g. adverse effects, lack of belief in treatment, psychological problems and poor patient-health care provider relationship). Interventions to minimise the adverse effects have been used in an attempt to improve the adherence to the endocrine treatment therapies, but it is not known whether these do actually improve adherence. Similar, it has been assumed that interventions by health professionals (doctors, nurses and pharmacists) will improve the adherence, but this has not been tested. In conclusion, in women with breast cancer, we know there is a problem with adherence. There are also many approaches and suggestions about how to improve adherence to the oral endocrine treatments, but none of these approaches/suggestions have been scientifically tested, and they need to be.