Pancreatic cancer is one of the most lethal malignancies. The overall median survival even with treatment is only 6–9 months, with almost 90% succumbing to the disease within a year of diagnosis. It is characterised by an intense desmoplastic stroma that may contribute to therapeutic resistance, and poses significant challenges for genomic sequencing studies. It is recalcitrant to almost all therapies and consequently remains the fourth leading cause of cancer death in Western societies. Genomic studies are unveiling a vast heterogeneity of mutated genes, and this diversity may explain why conventional clinical trial designs have mostly failed to demonstrate efficacy in unselected patients. Those that are available offer only marginal benefits overall, but are associated with clinically significant responses in as yet undefined subgroups. This chapter describes our current understanding of the genomics of pancreatic cancer and the potential impact of these findings on our approaches to treatment.