Recent studies have associated alterations of neuronal plasticity in specific brain areas with suicidal behavior. The Notch signaling pathway plays a relevant role in the control of stem cell maintenance, cell migration, and neuronal plasticity. In the present study, the gene expression of the four Notch receptors (NOTCH1-4), the five canonical ligands (DLL1, DLL3, DLL4, JAGGED1, and JAGGED2), the two non-canonical ligands (DLK1 and DLK2), and the transcription factors (HES1, HEY1, and HEY2) were measured in the dorsolateral prefrontal cortex (DLPFC) and amygdala (AMY) of suicide victims (S; n = 13 males, with no clinical psychiatric history and non-treated with anxiolytic or antidepressant drugs) and their corresponding controls (C; n = 13 males) by real-time PCR. The results revealed a reduction of NOTCH2 and NOTCH1, NOTCH3, and NOTCH4 gene expression in the DLPFC and AMY of S compared with C, respectively. DLL1 levels were increased in the DLPFC and decreased in the AMY, whereas DLL4, JAGGED1, and JAGGED2 were significantly decreased in the regions analyzed. DLK1 was reduced in the AMY, whereas no changes were observed in the DLPFC and in DLK2 expression levels in any of the regions analyzed. HES1 was significantly reduced in both brain regions from S, whereas there were no significant changes in HEY1 and HEY2. This study provides evidence suggesting that the Notch signaling pathway could be a potential key target in the treatment of suicidal behaviors.