Female sexual desire appears to be in part androgen dependent, which has lead to the use of testosterone in women for low libido. Despite this benefit, the long-term safety of testosterone as a hormone replacement or therapy has not been well established. Side effects of testosterone therapy include mild and reversible acne and hirsuitism, as well as changes to the lipid profile with oral, but not transdermal testosterone. Short-term studies, up to 2 years, have shown that for serum plasma testosterone levels at the upper portion or slightly above the reference range for reproductive-aged women, testosterone does not increase the risk of hepatotoxicity, endometrial hyperplasia, or behavioral hostility. No adverse cardiovascular effects including changes in blood pressure, blood viscosity, arterial vascular reactivity, hypercoagulable states, and polycythemia have been shown. Data is mixed with outcomes of breast cancer risk, with some experimental studies suggesting a decrease in estrogen-induced breast epithelial proliferation with low dose testosterone. Additionally, models of superphysiologic testosterone levels, such as polycystic ovarian disease, have not shown an increased risk of breast cancer. As with all hormone therapy in postmenopausal women, testosterone therapy should be individualized and requires that each woman weigh the risk and benefits. Nevertheless, only long-term safety studies will provide conclusive evidence as to testosterone safety in women.