High-temperature thermoplastic polymers have made significant inroads in medical device applications during the last 20 years. These materials are characterized by their high heat resistance (>200°C); their strength, toughness, and durability; their ability to withstand several cycles and doses of all types of radiation; their ability to be molded into parts with extremely tight tolerances; their biocompatibility; and their long-term durability. The need for higher-temperature and higher-performance materials has led to the use of aromatic polysulfones (PSUs), aromatic polyimides, aromatic polyketones, and aromatic polysulfides in demanding components and applications like medical trays, surgical and dental instruments, medical electronic components, drug delivery components, and machined parts. Fluoropolymers have been used in packaging, tubing, insulating materials, endoscopic, endocardial and endotracheal devices, catheter liners, and surgical instruments. High-performance engineering thermoplastics comprise about 8% of all plastics used in medical devices. This chapter will discuss the use of aromatic polysulfones, aromatic polyimides, aromatic polyketones, aromatic polysulfides, and various fluoropolymers.