Acute lobar nephronia (acute focal bacterial nephritis) has recently been recognized as an infectious process of the kidney. It is a radiologic diagnosis characterized as a nonliquifiable inflammatory renal mass associated with signs and symptoms of bacterial pyelonephritis. We present the successful management of a renal allograft recipient who had radiologic evidence of acute lobar nephronia within the graft six weeks after placement of an internalized ureteral stent.