Adherence is a potentially significant issue in oral therapy for breast cancer. Suboptimal adherence to medication regimens impacts clinical benefit and can result in treatment resistance, disease progression, and even death. Nonadherence is a greater issue with oral medications because the majority of responsibility shifts from healthcare professionals to the patient. Improving adherence to medication regimens can impact patients' likelihood of successful clinical outcomes. Many factors contribute to adherence behavior, such as complex dosing or administration requirements, cost, and a lack of understanding of the importance of adherence. Most of the factors are controlled by the patient, but nurses can play a significant role by monitoring patients, identifying potential barriers to adherence, and implementing intervention strategies. If barriers to adherence with oral therapies cannot be overcome, the use of IV therapies with equivalent efficacy and acceptable safety should be considered. Using IV medication, when available, can improve outcomes by ensuring that the patient receives the correct and optimal dose of medication at every cycle.