Tamoxifen and aromatase inhibitors are associated with side effects which can significantly impact quality of life (QoL). We assessed QoL in the Tamoxifen Exemestane Adjuvant Multinational (TEAM) Trial and compared these data with reported adverse events in the main database. 2,754 Dutch postmenopausal early breast cancer patients were randomized between 5 years of exemestane, or tamoxifen (2.5-3 years) followed by exemestane (2.5-2 years). 742 patients were invited to participate in the QoL side study and complete questionnaires at 1 (T1) and 2 (T2) years after start of endocrine treatment. Questionnaires comprised the EORTC QLQ-C30 and BR23 questionnaires, supplemented with FACT-ES questions. 543 patients completed questionnaires at T1 and 454 patients (84%) at T2. Overall QoL and most functioning scales improved over time. The only clinically relevant and statistically significant difference between treatment types concerned insomnia; exemestane-treated patients reported more insomnia than tamoxifen-treated patients. Discrepancy was observed between QoL issue scores reported by the patients and adverse events reported by physicians. Certain QoL issues are treatment- and/or time-specific and deserve attention by health care providers. There is a need for careful inquiry into QoL issues by those prescribing endocrine treatment to optimize QoL and treatment adherence.