['The irradiation of blood components is used to inactivate T-lymphocytes to prevent transfusion-associated graft-versus-host (GVH) disease in susceptible recipients. X-irradiation can be used as an alternative to gamma irradiation and does not involve the use of a radioactive source. This study investigated the effect of X-irradiation on the quality of various red cell concentrates (RCC).', 'Whole blood units were processed into RCC in additive solution (SAG-M) or RCC in plasma suitable for intra-uterine (IUT) or neonatal exchange transfusion. RCC-SAG-M were irradiated at day 14 and sampled before and 0, 7 and 14 days following irradiation. RCC-IUT and RCC-Exchange were irradiated on day 4 and sampled before and 0 and 24 h following irradiation. Extracellular potassium levels and free plasma haemoglobin (haemolysis) were compared in X or gamma-irradiated units during storage.', 'X-irradiation of RCC in SAG-M, or RCC for IUT or Exchange resulted in haemolysis comparable with gamma irradiation and levels were below the current UK/CE limit of 0.8% at the end of shelf life. X-irradiation of RCC-SAG-M or RCC-IUT with haematocrit of 75% and 85% resulted in potassium leakage comparable with gamma-irradiation. However, X-irradiation of RCC for neonatal exchange transfusion showed statistically significantly higher supernatant potassium levels after 24 h than gamma irradiation, although this difference is considered to be clinically insignificant.'] Does effect of X-irradiation on the quality of red cell concentrate?