A 54 year old lady with underlying chronic lung disease on long term oxygen therapy and end stage renal disease of unknown aetiology on regular haemodialysis for two years started developing progressive shortness of breath during her routine haemodialysis. She was unable to tolerate her haemodialysis sessions which had to be terminated prematurely in view of her symptoms despite adjustment of her dry weight and treatment of anaemia. She was not in chronic fluid overload and her symptoms always worsened after initiation of haemodialysis and improved after termination of haemodialysis. She was admitted to hospital for further investigations and initially treated for a lung infection but her symptoms did not improve. A computed tomography pulmonary angiography did not reveal any evidence of pulmonary embolism, and was consistent with chronic fibrotic changes. Her hypoxemia was concluded to be due to her underlying chronic lung disease, worsened by alveolar hypoventilation during haemodialysis. Her symptoms improved slightly with supplemental oxygen during her routine haemodialysis but we had to shorten her haemodialysis duration to 3 hours.