Cutaneous manifestations of graft-versus-host disease (GvHD) are the most common complication of allogeneic hematopoietic stem cell transplantation. We delineate the acute and chronic forms of GvHD, emphasizing their distinct clinical presentations, with acute GvHD commonly manifesting as a morbilliform rash and chronic GvHD exhibiting poikiloderma, lichenoid, and sclerodermoid changes. The pathophysiology, risk factors, and prognostic implications of GvHD are detailed, including the impact of donor-recipient HLA disparity and transplant conditioning regimens. Diagnostic criteria and therapeutic strategies are explored, highlighting the use of topical corticosteroids, systemic immunosuppressants, and extracorporeal photopheresis. The chapter underscores the importance of early recognition and multidisciplinary management to reduce morbidity and improve survival in affected patients.