There is not any information about [GABA] and [GABA]/[GLX] balance in human brain in acute phase of mTBI, but animal studies have shown alterations in concentrations of major inhibitory and excitatory neurotransmitters. [GABA-], [GABA+] and [GLX] were studied in vivo using MEGA-PRES pulse sequence in young patients (mean age - 16±2) with acute phase of mTBI. [GABA-]/[GLX] was significantly increased (p<0.05) in patients and [GABA-]/[tCr] had a trend for increase (p=0.09). This results correlates with animals experiments. [GABA+] didn't show any effects. Thus, [GABA-] MEGA-PRESS is more preferable for accurate [GABA] estimation.