The aim of the study was to check whether the plasma levels of brain-derived neurotrophic factor (BDNF), interleukin-8 (IL-8), interleukin-11 (IL-11) and ubiquitin C-terminal hydrolase L1 (UCHL-1) change in children with mild head trauma (N = 29) compared to controls (N = 13). Protein concentration in children with mild head trauma (12 children with mild concussion without loss of consciousness and 17 children with severe concussion and loss of consciousness) and the control group were measured by means of the Enzyme-Linked Immunosorbent Assay (ELISA) method. IL-8 and BDNF concentration was statistically higher in the group of children with mild head trauma (9.89 pg/mL and 2798.00 pg/mL, respectively) compared to the control group (7.52 pg/mL and 1163.20 pg/mL, respectively). BDNF concentration was significantly higher in children with severe concussion and loss of consciousness (3826.00 pg/mL) than in the control group. None of the tested proteins differed significantly between children with mild concussion without loss of consciousness and children with severe concussion and loss of consciousness. BDNF and IL-8 may be sensitive markers of brain response to mild head trauma in children. The lack of statistical differences for BDNF and IL-8 between children with mild or severe concussion could indicate that their elevated levels may not result from significant structural brain damage but rather reflect a functional disturbance.