Postmenopausal patients with hormone-sensitive breast cancer may be eligible for adjuvant hormone therapy. - For years, tamoxifen was the treatment of choice. - However, the side effects associated with tamoxifen, such as endometrial cancer and thromboembolic disorders, and the search for more effective agents have led to the introduction of new hormonal therapies. - The results of randomised trials with the third-generation aromatase inhibitors anastrozole, exemestane and letrozole demonstrate improved efficacy compared to tamoxifen. - Using aromatase inhibitors, the disease-free survival is prolonged and recent data from some studies also show a benefit in overall survival. - Aromatase inhibitors are associated with specific side effects consisting of osteoporosis/increased incidence of fractures and myalgia/arthralgia.