Human biomonitoring (HBM) is a crucial tool for measuring chemical and metabolite levels in human biological media, along with the organism’s biological and biochemical responses to these chemicals. The benefits of HBM include its ability to reflect an organism’s total exposure to chemicals and its closer connection to individual health effects. This chapter explores the opportunities and limitations of HBM studies, the general requirements for obtaining accurate results, and the reliability of analytical methods and biomarkers. Additionally, the specific use of breast milk as an HBM medium is examined in detail. The evaluation of HBM data, using guidance values and biomonitoring equivalents, is also summarized comprehensively. Moreover, the fundamentals of estimating human health risks linked to a substance through reverse dosimetry or hazard quotients (HQ) are discussed. In the later sections, the estimation and application of statistically derived reference values, along with the essentials of communicating HBM results, are presented.