Gamma-irradiation of blood components is regarded a safe procedure used for prevention of transfusionassociated graft-versus-host disease. However, reports showed that irradiation can cause erythrocyte haemolysis and damage to the RBC membrane. In Universiti Kebangsaan Malaysia Medical Centre (UKMMC), a number of suspected transfusion reactions (TR) featured unusual isolated episodes of red-coloured-urine or haemoglobinuria among paediatric patients without clinical features of acute haemolytic TR. Haemolysis of irradiated red cells was suspected as a cause. This study was conducted to evaluate haemolytic changes of RBC components following irradiation. A prospective, pre- and post- irradiation comparative study was conducted on 36 paired RBC-components in the blood-bank, UKMMC in the year 2013. Samples were tested for plasma-Hb, percent-haemolysis, plasma-potassium (K+) and lactate dehydrogenase (LDH) level. Post-irradiation mean plasma-Hb and percent-haemolysis were significantly higher than pre-irradiation values at 0.09±0.06g/dl VS 0.10±0.06g/dl and 0.19±0.13% VS 0.22±0.13% respectively, while plasma-K+ and LDH values did not show significant difference. However, the mean percent-haemolysis level was still within recommended acceptable levels for clinical use, supporting that irradiated RBC units were safe and of acceptable quality for transfusion. There was no conclusive reason for isolated haemoglobinuria following transfusion of irradiated red-cell products. Further research is suggested to investigate the other possible causes.