In this paper, we describe the case of a patient with end-stage renal disease (ESRD) undergoing continuous ambulatory peritoneal dialysis (CAPD) who had developed septic arthritis of the shoulder further complicated by abscess formation. A 29-year-old male hemiplegic patient (two months post-stroke) with ESRD undergoing CAPD was hospitalized for rehabilitation. He developed painful shoulder while receiving antibiotic therapy. The patient was diagnosed as having septic arthritis with abscess formation. Magnetic resonance imaging of the right shoulder demonstrated multilocular fluid collections in the subacromial and subdeltoid regions including the subscapularis and deltoid muscles. He was treated with vancomycin and followed up by serial C-reactive protein measurements. His shoulder motions returned to near-normal at the end of therapy including physical therapy interventions as well. As part of the differential diagnosis of shoulder pain in ESRD patients, we want to draw attention to septic arthritis, which can be further complicated by abscess formation, as in our case. Turk J Phys Med Rehab 2011;57:57-9.