The perioperative period presents unique challenges that require careful coordination across disciplines. Perioperative consultation is increasingly recognized as a critical aspect of surgical care, with growing emphasis on shared responsibility between internal medicine and anesthesiology. The complexity of modern surgical patients, including older, multimorbid, and often receiving multiple medications, demands a structured, evidence-based, and collaborative approach to management and risk reduction. Effective co-management models rely on interprofessional collaboration that leverages the unique strengths of each specialty: internal medicine provides expertise in chronic disease optimization, risk stratification, and longitudinal care, while anesthesiology brings expertise in intraoperative physiology, acute pain management, and immediate post-anesthesia recovery. Together, they can ensure comprehensive assessment, improve communication, minimize perioperative complications, and facilitate smoother transitions of care. This chapter reviews the principles of perioperative consultation, outlines the roles of internal medicine and anesthesiology, highlights models of collaboration, and explores barriers and enablers to effective co-management. Special attention is given to the value of risk stratification, optimization of comorbidities, communication frameworks, and enhanced recovery pathways. By fostering mutual respect and collaboration, perioperative consultation evolves from a transactional task to a coordinated model that improves safety, efficiency, and patient-centered outcomes.