AIM: Our study aimed to demonstrate whether agmatine could regulate proliferation and cell fate determination of subventricular zone neural stem cells (SVZ NSCs). MAIN METHODS: SVZ NSCs were grown in the presence of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) (20ng/ml) until 4days in vitro (DIV) and later the culture medium was replaced without EGF and bFGF until 11 DIV in the absence (EGF/bFGF(+/-)/Ag(-)) or presence of agmatine (EGF/bFGF(+/-)/Ag(+)). Another set SVZ NSCs were maintained with EGF and bFGF until 11 DIV without (EGF/bFGF(+/+)/Ag(-)) or with agmatine treatment (EGF/bFGF(+/+)/Ag(+)). Agmatine's effect on proliferation and cell death (H and PI staining and Caspase-3 immunostaining) was examined at DIV 4 and 11. Agmatine's (100μM) effect on cell fate determination was confirmed by immunostaining and Western blot at 11 DIV. KEY FINDINGS: Agmatine treatment reduced the neurosphere size and total cell count number dose-dependently in all the experimental groups both at DIV 4 and11. Immunoblotting and staining results showed that agmatine increased the Tuj1 and MAP2 and decreased the GFAP with no change in the Oligo2 protein expressions. This neurogenesis effect of agmatine seems to have a relation with ERK1/2 activation and anti-astrogenesis effect is thought to be related with the suppression of BMP 2,4 and SMAD 1,5,8 protein expression. SIGNIFICANCE: This model could be an invaluable tool to study whether agmatine treated SVZ NSC transplantation to the CNS injury could trigger neurogenesis and decrypt the full range of molecular events involved during neurogenesis in vivo as evidenced in vitro.