The role of Notch signalling in congenital cardiovascular disease is evident by the identification of human mutations in several Notch signalling components, which also indicates the importance of activated Notch pathway in cardiovascular biology. Therefore, the aim of the present study is to investigate the expression pattern of the components of Notch signalling molecules and their role in mice embryonic heart and vascular development. Group A: normal control pregnant mice, group B: pregnant mice were injected with DMSO, group C: DAPT were subcutaneously injected to pregnant mice. The morphological and molecular changes of trabeculation-defective phenotype were analysed using histological, scanning electron microscope, immunoblot, immunolocalization and reverse transcriptase-PCR. E15.5 DAPT-treated mice revealed that there was a major reduction in the formation of septal walls between the ventricular chambers compared with normal control pregnant mice. VEGF expression was found in the DAPT treated and wild-type embryonic artery, whereas notch target genes GATA4, Hey1 expression were not found in the DAPT treated mice embryo. The role of Notch in ventricular development is supported by the trabeculation-defective phenotype seen in standard and endocardial-specific inhibition of Notch targets. The present study reveals the significant role of Notch signalling during the formation of ventricular septum and proper development of endothelial cell lineage and its precursor in mice cardiogenesis.