A hemodialysis patient with insulin-dependent diabetes mellitus and a non-functioning renal allograft in whom fever, low blood pressure, and confusion developed is reported. She underwent extensive evaluation and allograft nephrectomy for emphysematous pyelonephritis that was diagnosed by the presence of air in the collecting system of the transplanted kidney during computerized tomography of the abdomen. In nine patients with emphysematous pyelonephritis in renal allografts reported previously, this is the first instance of emphysematous pyelonephritis in a renal allograft with coagulase-negative staphylococcus.