This chapter provides an in-depth examination of the biological studies of nanocomposites used in implants and drug delivery systems. It highlights the diverse types of nanocomposites and their specific roles in advancing medical technologies. The chapter begins with a detailed overview of the properties and functionalities of these nanocomposites, focusing on their biocompatibility, mechanical strength, and drug release capabilities. Polymer nanocomposites are known for their biocompatibility and ability for smart drug delivery, while ceramic nanoparticles like hydroxyapatite and bioactive glasses are examined for their osteoconductive properties and integration with bone tissues. Metallic nanoparticles, including titanium and silver, are reviewed for their structural support and antimicrobial effects in implants. Further, recent key studies on how these materials interact with biological systems, addressing cellular responses, tissue integration, and immune system interactions, are reviewed. Through case studies, the chapter illustrates the design and performance of nanocomposite-based implants and drug delivery systems, demonstrating their potential to enhance healing processes and treatment efficacy. The chapter concludes by discussing the current challenges and future directions in nanocomposite research, including strategies for further improvement in performance of implants and drug delivery agents, regulatory considerations, and long-term safety profiles. This comprehensive analysis aims to offer valuable insights into how nanocomposites are transforming the fields of medical implants and drug delivery technologies.