<p>Excitatory/inhibitory balance, oxidative and antioxidative regulatory systems play a role in the pathophysiology of epilepsy. In addition, intestinal dysbiosis is also involved in the pathophysiology of epilepsy. The aim of this study was to investigate the effects of <i>Lacticaseibacillus rhamnosus GG</i> (<i>L. rhamnosus</i> or LBR) on epileptic seizures and gamma aminobutyric acid (GABA), malondealdehyde (MDA), superoxide dismutase (SOD, glutathione peroxidase (GPx) and catalase (CAT) levels in serum and brain tissue in a penicillin-induced acute seizure model in rats. The study included 70 adult <i>Wistar albino</i> rats, which were divided into 10 groups: Control(CONT), Penicillin (PEN), only LBR-4 (OLBR-4), Diazepam-4 + Penicillin (DZM-4 + PEN), LBR-4 + Penicillin (LBR-4 + PEN), LBR + Diazepam-4 + Penicillin (LBR-DZM-4 + PEN), only LBR-10 (OLBR-10), Diazepam-10 + Penicillin (DZM-10 + PEN), LBR-10 + Penicillin (LBR-10 + PEN), and LBR + Diazepam-10 + Penicillin (LBR-DZM-10 + PEN). 1 × 10¹⁰ cfu/mL of <i>L. rhamnosus</i> was given to the <i>L. rhamnosus</i> groups via gavage for 4 or 10 weeks depending on the duration of administration. The DZM groups received 2&#xa0;mg/kg DZM intramuscularly. The rats were anesthetized and electrodes were placed in the somatomotor area after the left side of the skull was opened. Penicillin was administered intracortically and ECoG was recorded for 120&#xa0;min. Levels of GABA, MDA, SOD, CAT, and GPx were determined using the ELISA method. <i>L. rhamnosus</i> administration reduced spike-wave frequency (SWF), total spike-wave frequency (TSWF), spike-wave amplitude (SWA), and MDA levels (<i>p</i> &lt; 0.05). In contrast, it increased levels of GABA, SOD, CAT, and GPx (<i>p</i> &lt; 0.05). <i>L. rhamnosus</i> may exert a preclinical antiepileptiform effect in an acute seizure model of epilepsy.</p>