Dioxin is a generic term for a class of 210 individual chlorine-containing organic compounds of a similar chemical structure. The reason they have generated major environmental concern is due to their ubiquitous nature and their potentially harmful effects on human health, even at very low levels. Dioxins are generally produced as unwanted by-products during thermal processes involving the burning of organic material or following chemical manufacture and some industrial processes. Human exposure to dioxins occurs mainly as a consequence of ingestion and typical health effects are recorded in the paper. The methodology for the sampling of dioxins is obviously dependent on the circumstances and locations in which they occur. However, details of standard sampling methods from emission sources, ambient air solids and liquids are reviewed. Due to the safety concerns and low concentrations usually present, the subsequent analysis of dioxins is specialized and requires dedicated facilities. Samples generally require extensive extraction and clean-up prior to analysis, with the final determination being carried out by gas chromatography linked with high-resolution mass spectrometry. These procedures are discussed. All of the methods employed have stringent quality control procedures to ensure the highest quality data. The reporting of the final analytical results is also described.