Pyocystis is an important complication of non-functioning urinary bladder, which often poses diagnostic difficulties. We present a case of pyocystis in a patient on chronic hemodialysis who was anuric for one year. The patient was initially diagnosed with diverticulitis. An abdominal C-T scan suggested the diagnosis of pyocystis, which was confirmed by bladder catheterization. The patient was treated with bladder drainage and a prolonged antibiotic course, followed by intermittent saline washing of the bladder.