Biologic therapies are becoming the preferred treatment option for many complex medical conditions, especially in the areas of oncology and immunology. Cytokines, monoclonal antibodies, and immunomodulators all have their own specific roles, clinical applications, mechanisms of action, and side effects. As newer biologic agents are approved and used for treatment, the nurse involved in the care of the patient receiving parenteral biologic therapy or in the administration of parenteral biologic therapies must know and understand the technology and mechanisms of action associated with these agents as well as guidelines for their safe administration to ensure positive patient outcomes. This article discusses biologic therapies, focusing on monoclonal antibodies used in oncology and immunology. The indications, use, and administration of parenteral biologic therapies, as well as the nursing management of the patients receiving the therapies, are presented.