PURPOSE: Published literature describing the effectiveness of outpatient oncology services delivered by clinical pharmacists is summarized. METHODS: Peer-reviewed articles on studies evaluating the provision of outpatient oncology services by licensed clinical pharmacists in the United States were identified and screened according to a study-specific protocol. Only research publications focused on the care of oncology patients and indicating the evaluation of measurable services and outcomes were selected for review. Data from eligible studies were extracted using a standardized tool, and agreement by a majority of the investigators was required for inclusion of articles in the final review. RESULTS: Eight publications were included in the review; nearly all were published since 2010. All of the included articles reported on results of observational studies in which data sourced from surveys, existing medical or prescription records, or medical cost information were analyzed to measure patient or provider satisfaction (or both) or patient-reported health outcomes. The evaluated evidence indicated that pharmacists were effective in identifying treatment issues and medication misuse, delivering satisfactory and valued services, and finding mechanisms to reduce medical costs or generate revenue to justify continuation or support expansion of clinical pharmacy services. Moreover, in two instances, pharmacists' services were associated with improvements in symptoms reported by oncology patients. CONCLUSION: Available evidence suggests that outpatient oncology practices may benefit from integrating pharmacists into care models in order to more effectively, efficiently, and holistically address the needs of patients with cancer.