This guidebook describes the facilities, equipment and analytical methods required to determine the concentrations of various radionuclides in environmental materials and foodstuffs. Contents: 1. Introduction; 2. Pathways and samples of interest; 3. Radionuclides of interest; 4. Requirements for laboratories, equipment and personnel; 5. Collection and preparation of samples; 6. Analytical methods; 7. Analytical quality control; References: Sections 1–7; Bibliography: Sections 1–7; Annex I: Method for determining gamma emitters; Annex II: Methods for radiochemical analysis of strontium; Annex III: Method for radiochemical analysis of tritium; Annex IV: Methods for radiochemical analysis of plutonium, americium and curium; Annex V: Units, prefixes and symbols; Annex VI: Nuclear accident scenarios; Annex VII: Radionuclide data; Annex VIII: Grass sample collection; Annex IX: Gamma spectrometric systems; Annex X: Potential suppliers of calibration sources and reference materials.