CASE PRESENTATION: A 67 YO male with PMHx of end stage renal disease on PD since 2013, coronary artery disease, diabetes, atrial fibrillation, and hypertension. Patient presented with complaints of shortness of breath and generalized weakness x 2 days. He was found to be hypoxic with O2 saturations in the 80s, his other vital signs were WNL. CXR revealed a large left sided pleural effusion. Patient had undergone thoracentesis three times in the past for recurrent effusions however the cause of his effusions was never identified. On this instance, thoracentesis was performed and workup revealed a transudative fluid with a glucose gradient of 14 mg/dL. All other fluid and serum studies returned within acceptable limits. Suspicion of a pleura-peritoneal communication was low because of the low glucose gradient in the peritoneal fluid as well as the fact that this was a left sided effusion. Nonetheless, peritoneal scintigraphy was conducted and demonstrated a pleuro-peritoneal communication. Patient was transitioned to hemodialysis and achieved complete resolution of his symptoms.