Human exposure to toxic, environmental chemicals can be assessed by measuring levels of parent chemicals or their metabolites in biological matrices such as urine, plasma, and whole blood. This technique is known as biomonitoring. If these measurements are accurate, the internal dose of the target chemicals in humans can be estimated. Biomonitoring has become an important tool for epidemiological studies linking exposures to toxic, environmental chemicals to health outcomes. Selection of the appropriate biological matrices for biomonitoring is crucial and requires a comprehensive understanding of the physiochemical properties of the target chemicals, their toxicokinetic properties, as well as the biological properties of the matrix. Different matrices may provide different information on the magnitude and frequency of dose, toxicity, and biological endpoint. Saliva has been used as a matrix for biomonitoring of toxic, environmental chemicals, but with far less frequency than urine or plasma. The success of using saliva as a matrix for exposure assessment has been proven for cotinine, a principal metabolite of nicotine. However, a number of limitations and challenges remain for other chemicals such as plasticizers and heavy metals. In this chapter, the current knowledge on salivary biomonitoring is provided, including the associated challenges researchers face. More importantly, practical recommendations are provided with the intention of supporting future research using saliva as a matrix to assess exposure to toxic, environmental chemicals.