INTRODUCTION: Schizophrenia is one of the most severe psychiatric disorders with about 1% prevalence. It has been proved that glutamatergic N-methyl-d-aspartate (NMDA) receptor antagonists such as MK-801 and phencyclidine cause schizophrenia-like behaviours in rodents. Agmatine is an endogenous amine synthesized from decarboxylation of arginine and has been thought to be a neurotransmitter/neuromodulator. It binds to imidazoline and alfa adrenergic receptors and blocks cation channelled receptors, such as nicotinic acetylcholine, 5-HT3 serotonergic, and NMDA receptors. It is an endogenous inhibitor of nitric oxide synthase. A limited number of studies showed that agmatine attenuates sensorimotor gating deficit, which is an important parameter for schizophrenia, and improves cognitive deficits in rats. Despite this, it has also been shown that high doses of agmatine impaired sensorimotor gating. Herein, the aim of our study is to investigate the effect of subchronic agmatine treatment on sensorimotor gating, visual recognition memory, and social functions in subchronic MK-801 model of schizophrenia in rats.