Lymphocele is a lymphocyte-rich fluid collection that results from disruption of lymphatics in the recipient during renal transplantation. While small collections resolve spontaneously, larger, symptomatic ones may cause obstructive nephropathy requiring percutaneous or laparoscopic drainage. Prompt diagnosis using bedside sonography may obviate the need for renal replacement therapy. Herein, we present a case of a 72-year-old kidney transplant recipient who developed allograft hydronephrosis secondary to compression by a lymphocele.