Surrogate matrix has been widely used in bioanalysis, especially for endogenous compounds analysis. Surrogate analyte approaches, on the other hand, are only occasionally employed in bioanalysis, but play a significant role and serve as a useful tool for the quantitation of various analytes, ranging from small molecular biomarkers to large molecule biological entities. This webinar will give a brief review of the surrogate analyte approaches during bioanalysis using LC-MS platform, from both scientific and regulatory perspectives. A few case studies will be discussed in detail laying out the challenges, and approaches to tackle these challenges.