Severe anaemia in children is a life-threatening condition that is amenable to prompt blood transfusion. Previous data reported that the transfusion of 5 ml/kg body weight of packed red blood cell (PRBC) increased the haemoglobin (Hb) concentration by about 1g/dl. This study was aimed at assessing the increment in Hb concentration after PRBC transfusion in children using 10ml/kg body weight. This was a longitudinal observational study carried out in the Children Emergency Room of a tertiary center in Nigeria and involved 108 children aged 1-10 years without active bleeding or significant haemolysis that were transfused with10ml/kg body weight of PRBC. The Hb concentration was measured using a portable haemoglobinometer before the blood transfusion,1,6, 12 ,24 and 48th-hour after blood transfusion. The mean age of the participants was 4.6 ± 2.7 years with a male to female ratio of 1:0.7. A total of 52.8% and 59.2% of the participants had pre transfusion Hb levels of 5g/dl or less and received between 150-250mls of packed red cells respectively. The mean pre-transfusion Hb concentration was 5.1±1.4 g/dl while the mean post-transfusion Hb concentration was10.5 ±1.3g/dl. Accordingly, transfusion of 10ml/kg body weight of PRBC increased Hb concentration from its baseline by approximately 5g/dl. In conclusion, there is a Hb rise of 5g/dl after transfusion of 10ml/kg of PRBC..