OBJECTIVE: Aim of our study was to evaluate distribution of ABO and Rh blood type groups in children after hip surgery regarding transfusion administration and fever presence. METHODS: Four types of ABO blood groups (A; B; AB; O) and 2 types of Rh blood groups (Rh+; Rh-) were evaluated in group with administered transfusion (tr+) and without given transfusion (tr-); and in group with fever (fev+) and without fever (fev-), in 146 children after hip surgery. Tr+ and fev+ groups were divided into 3 groups (0-24h; 25-48h; 49-72h): for tr+ group (Group 1, Group 2, Group 3), and for fev+ group (Group A, Group B, Group C). RESULTS: AB blood group significantly decreased in Group 1 (χ2= 6.44; p<0.05) and A blood group in Group 3 in tr+ group (χ2= 7.68; p<0.01). O blood group significantly increased in Group 3 in tr+ group (χ2= 9.96; p<0.01). AB blood group significantly decreased in Groups B (χ2= 12.2; p<0.01) and C (χ2= 4.2; p<0.05) in fev+ versus fevgroup. B blood group significantly increased in Group C (χ2= 34.4; p<0.01) in fev+group. CONCLUSION: Administration of transfusion and fever onset in pediatric patients undergoing surgical correction of the hip is not influenced by the ABO and Rh blood groups system in humans. There is correlation between distribution of ABO blood groups with the time of transfusion administration and fever onset in children after hip surgery.