Biologics are often used to treat a range of life-threatening and debilitating conditions — such as cancer, autoimmune diseases, and kidney disease — and represent an increasing treatment option for patients in the United States. A biosimilar version of the biologics can be produced, which is a highly similar version of the medicine with no clinically meaningful difference in effectiveness or safety from the innovator biologic. This Fast Fact presents an analysis of site-of-treatment price differentials for innovator biologics and biosimilars.