Litopenaeus vannamei, commonly known as white leg shrimp, has dominated the global shrimp industry owing to its superior yield performance, high tolerance to disease, and fast production cycle. It is also highly demanded by consumers for its desirable flavor. To quantitatively assess the quality of white leg shrimp, gas chromatography/mass spectrometry (GC/MS) analysis is often used. It can detect both volatile and non-volatile compounds that influence shrimp's nutritional and sensory quality. Although many studies have employed GC-MS-based metabolite profiling on white leg shrimp, detailed guidance on conducting such analyses remains limited. On the other hand, such guidance is essential to support researchers who are new to this field and to aid in the development of quality assessment methods for white leg shrimp. Therefore, this chapter aims to provide a comprehensive guide on GC/MS analysis for white leg shrimp. In this chapter, a step-by-step procedure will be discussed, starting from sample preparation, extraction, and derivatization, until the injection of the samples into the GC-MS instruments.