The purpose of this study is to determine the safety and efficacy of acupuncture as a complementary therapy to pain medication for joint pain associated with aromatase inhibitors for breast cancer treatment. Breast cancer patients are living longer largely due to the benefits of hormonal therapy. Aromatase inhibitors (AIs) are a new class of hormonal agents which block estrogen synthesis in postmenopausal women. However, musculoskeletal pain occurs in up to 50% of patients treated with AIs and often does not respond to conventional pain medications. AI-induced joint pain interferes with patient compliance and may cause major disability. Therefore, safe and effective treatments are needed to alleviate AI-induced musculoskeletal pain.