Obstruction of urine flow and urine leaks are potentially life-threatening complications in renal transplant patients. The diagnosis is difficult, and definite treatment may therefore be delayed. This paper reviews the clinical course of ten renal transplant patients with urologic complications, discusses the limitations of the standard tests used to investigate such problems, and describes the role of percutaneous antegrade pyelography and nephrostomy drainage catheter placement as safe and accurate diagnostic and therapeutic procedures.