Malignant transformation of normal cells is associated with the evolution of genomic alterations. This concept has led to the development of molecular testing platforms to identify genomic alterations that can be targeted with novel therapies. Next generation sequencing (NGS) has heralded a new era in precision medicine in which tumor genes can be studied efficiently. Recent developments in NGS have allowed investigators to identify genomic predictive makers and hereditary mutations to guide treatment decision. The application of NGS in gastrointestinal cancers is being extensively studied but continues to face substantial challenges. In our review, we discuss various NGS platforms and highlight their role in identifying familial mutations and markers of response or resistance to cancer therapy. We also provide a balanced discussion of the challenges that limit the routine use of NGS in clinical practice.