Lymphatic leak is a common cause of perirenal fluid collection in renal transplant patients in whom early recognition and therapy is essential for the survival of the kidney. Nuclear medicine offers dynamic renal scintigraphy for the evaluation of renal perfusion, function, and recognition of urologic complications. We present a renal transplant recipient in whom renal scintigraphy showed abnormal radiotracer collection adjacent to the bladder, which caused urinary stasis in the renal pelvis. Lymphoscintigraphy, which can be used to identify lymphatic collections, revealed abnormal radiotracer accumulation in the transplant fossa and confirmed that the perirenal fluid collection was the result of a lymphatic leak. We have described a patient with perirenal fluid collection after renal transplantation surgery in whom lymphoscintigraphy was used to confirm the diagnosis. Copyright © 2006 by Lippincott Williams & Wilkins.