There is an urgent need to develop alternative therapies against lethal pancreatic cancer (PC). Ocimum sanctum ("Holy Basil") has been used for thousands of years in traditional Indian medicine, but its anti-tumorigenic effect remains largely unexplored. Here, we show that extracts of O. sanctum leaves inhibit the proliferation, migration, invasion, and induce apoptosis of PC cells in vitro. The expression of genes that promote the proliferation, migration and invasion of PC cells including activated ERK-1/2, FAK, and p65 (subunit of NF-κB), was downregulated in PC cells after O. sanctum treatment. Intraperitoneal injections of the aqueous extract significantly inhibited the growth of orthotopically transplanted PC cells in vivo (p<0.05). Genes that inhibit metastasis (E-cadherin) and induce apoptosis (BAD) were significantly upregulated in tumors isolated from mice treated with O. sanctum extracts, while genes that promote survival (Bcl-2 and Bcl-xL) and chemo/radiation resistance (AURKA, Chk1 and Survivin) were downregulated. Overall, our study suggests that leaves of O. sanctum could be a potential source of novel anticancer compounds in the future.