Haemolysis interferes with many test results through release of red blood cell (RBC) intracellular contents or via spe- cific analytical interferences. In grossly haemolysed sample, potassium level can be raised considerably dependent on the degree of haemolysis and may exceed the critical limit value. In this case report, the potassium level from a grossly haemolysed sample taken after haemodialysis remains within normal range, and this has led to unnecessary repeated blood samplings hence delay the diagnosis. With the persistently high haemolytic index (HI) of 400mg/ dL and normal potassium levels in sequences of samples taken post haemodialysis should raise a high suspicion of in vivo haemodialysis related-haemolysis. An effective communication between laboratory and clinician, and a proper, well-designed protocol or guideline on the management of sample haemolysis in clinical laboratory therefore is very essential to ensure all clinically important but rare case of in vivo haemolysis can be identified early and the potential unwanted serious outcomes can be prevented accordingly.