Alpha-fetoprotein (AFP) is a tumor-associated fetal protein that promotes growth and well-being in the fetus during pregnancy and further serves as a biomarker for birth defects and various cancers. Although AFP regulates growth in both fetal and cancer cells, it can also inhibit cell growth in environments undergoing shock, stress, and inflammation. The present review addresses AFP and its derived peptides, not only as disease/disorder biomarkers, but as biologic response modifiers in multiple bodily functions and interactions. In order to present these events, the present treatise was divided into four discussion sections, namely, 1) AFP structure and function; 2) AFP as a human disease/disorder biomarker; 3) AFP-derived peptides in their role in cancer growth and metastasis; and 4) AFP peptides as potential biotherapeutic agents. Each section discusses and summarizes activities of AFP peptides in events such as cell migration, adhesion, cell-to-cell interaction, transduction signaling, angiogenesis, carcinogenesis, metastasis, and growth regulation.