AbstractBiologics are significant drivers of globally escalating healthcare costs. Biosimilars have potential to offer cost savings with comparable efficacy and safety to innovator products and increase the access of treatment to more patients. This study aimed to increase understanding and perception of biosimilars concept. It also described the pharmacoeconomic impact of biosimilar in oncology and formulary consideration of oncology biosimilars substituting with their originators in major oncology centers in the Saudi Arabia. A biosimilar is a biological product that is similar to a reference biopharmaceutical product. As the manufacturing process hinders the ability to identically replicate the structure of the original product, biosimilar cannot be described as an absolute equivalent of the original medication. Different regulatory agencies such as United States Food and Drug Administration, European Medicines Agency, and Saudi Food and Drug Authority have approved several biosimilars of oncology biologics. The experience of biosimilar use in Europe and USA provides valuable insights into the use of biosimilars. The widespread use of biosimilars has the potential to reduce healthcare expenditure, as well as improving access without compromising patient outcomes. There is a need for increasing awareness about biosimilars to improve acceptance rates. The use of biosimilar filgrastim in Ministry of National Guard Health Affairs, Saudi Arabia, has resulted in a significant cost saving annually. It was proposed that further substitution and switching to biosimilars in oncology would lead to major savings in resources.