Precision medicine is now becoming feasible with more advanced technology and in-depth biological information through clinical sequencing. However， still there are many limitations such as 1) tumor heterogeneity and proper sample availability， 2) technical validity， 3) proper target identification， 4) drug availability， and 5) unproven biology behind. Gastric cancer(GC) has been notorious for precision medicine due to difficulties of translational research with diverse heterogeneity. Fortunately， now we have reliable molecular subtypes of GC based on genomic data， which might not be prognostic but predictive for certain treatments. TCGA presented 4 subtypes of GC as EBV-related， MSI-high， chromosomal instable and genome stable， which could be used for deciding specific treatment based on each molecular characteristics. Also， there are several other subgroups based on different genomic information and RNA signatures. Especially using RNA expression could give us molecular characteristics of tumor microenvironment including immune signature which might be useful for future immune therapy in GC. However， for applying these genomic subgroups， the test including target gene sets and detection method should be validated and reproducible with feasible sample sources. Now we have more opportunities for precision medicine in GC including biomarker-driven umbrella trial. Our cooperative and integrative effort will support precision medicine in reality. Here， I will share the experiences of clinical sequencing and current status of GC umbrella trial including clinical sequencing.