Necrotic skin lesions are unfortunately common in patients with end stage renal disease undergoing dialysis therapy. We present a case of a necrotic skin lesion in a peritoneal dialysis patient shortly after the initiation of warfarin therapy for atrial fibrillation. We discuss and contrast distinguishing features of two diagnostic possibilities: warfarin skin necrosis (WSN) and calcific uremic arteriopathy (CUA) in terms of clinical presentation, risk factors and pathology. Lastly, we outline the importance of establishing a diagnosis as treatment regimens differ substantially.