Problem Identification: A lack of testing options for the diagnosis and prognosis of chronic graft-versus-host disease (cGVHD) is a barrier to clinical management. Studies that have investigated the role of blood proteins as diagnostic and prognostic biomarkers for cGVHD were reviewed. Literature Search: PubMed and Scopus databases were searched for articles published from January 1, 2000, to May 31, 2019. 660 articles were retrieved. Data Evaluation: The authors appraised seven articles based on the inclusion and exclusion criteria to summarize identified blood protein biomarkers for cGVHD. Synthesis: Several blood proteins were identified as potential diagnostic and prognostic biomarkers. Most of these proteins are thought to be key contributors in cGVHD pathogenesis and, therefore,... could be ideal biomarkers to guide clinical management. Implications for Practice: These biomarkers could aid providers in diagnosing cGVHD, identifying patients at high risk for development of cGVHD, and initiating preemptive therapy.