Adenosine has been shown to play a significant role as a modulator of neuronal activity in convulsive disorders, acting as an endogenous anticonvulsant agent. Any change in adenosine deaminase (ADA) levels will reflect to adenosine levels. In the present study, we have investigated the effect of glutathione on brain tissue ADA levels due to seizures induced by convulsive and subconvulsive dose of pentylenetetrazol (PTZ) in mice. ADA levels due to seizures induced by convulsive and subconvulsive pentylenetetrazol were measured using the Giusti method. ADA levels were higher in the experimental epilepsy groups than in the control and sham groups. ADA levels significantly decreased in the glutathione groups, which may have antiseizure effects. Decreased levels of ADA would be due to increased adenosine levels, protecting against oxidative stress.