BACKGROUND: Fibroblast activation protein alpha (FAP) is a serine protease that is expressed at basal levels in benign tissues but is overexpressed in a variety of pathologies, including cancer. Consequently, significant research efforts have been expended to develop diagnostic radiopharmaceuticals and effective radiotherapies that target this protein. The aim of this review is to summarize the current progress on the development of protein-based radiopharmaceuticals that target FAP. MAIN BODY: A literature survey spanning nearly 40 years was conducted to assess the historical development and current progress in protein-based radiopharmaceuticals that target FAP. To date, more than 20 publications have been introduced that describe these agents in preclinical and clinical settings. This review summarizes the development and evaluation of radiopharmaceuticals involving antibodies, antibody fragments, and single domain antibodies. CONCLUSION: The results of this literature review demonstrate that while significant research efforts have been expended on peptide-based radiopharmaceuticals and small molecule FAP inhibitors, the development of protein-based radiopharmaceuticals that target FAP remains an active research area that has yet to reach its full potential.