Exemestane is a third-generation aromatase inhibitor, which has proven to be a useful drug in the treatment of early stage breast cancer. Several clinical trials have been performed or are currently underway using exemestane as adjuvant therapy in postmenopausal women, which will be the indication reviewed here. A relative reduction in risk of breast cancer recurrence or death of 24% has been shown with exemestane compared with tamoxifen when given after 2 to 3 years of tamoxifen. This corresponded to a 3.3% absolute reduction in recurrence or death at the end of 5 years, for a number needed to treat of 30. The main use of exemestane in the adjuvant setting is as an alternative to tamoxifen, and toxicities are discussed in relation to tamoxifen toxicities. In general, patients receiving exemestane experience less hot flashes and more arthralgias in comparison to tamoxifen, while there is also a reduction in venous thromboembolic events and vaginal bleeding. Patients on exemestane as a group do not appear to have a significantly changed quality of life in comparison to tamoxifen, while having a statistically significant benefit in preventing breast cancer recurrence.