Advances in solid organ transplantation and immunosuppressive therapy have provided considerable improvement in morbidity and mortality and significant improvement in quality of life. Close clinical monitoring and imaging studies are invaluable tools for ensuring successful outcomes. Ultrasound is an excellent front-line, noninvasive imaging method for early postoperative allograft evaluation, and it can also provide valuable information for long-term follow-up. This article addresses the role of ultrasound in evaluating renal, hepatic, and pancreatic allografts and reviews the associated complications of solid organ transplantation. The authors have divided the complications into five major categories: allograft-associated collections, allograft dysfunction, vascular complications, posttransplant neoplasms, and recurrent native diseases as they apply to the various types of solid organ transplant. © 2008 Elsevier Inc. All rights reserved.