The aim with this handbook is to provide a practical, understandable and common way of measurement uncertainty calculations based on already existing quality control and method validation data for test procedures in routine use. To illustrate the approach the estimation of measurement uncertainty for some routine methods in environmental laboratories are presented. The approach follows the general ISO and EA guidelines for measurement uncertainty and uses the possibility of grouping the individual uncertainty components into different categories. The first category is the intermediate precision within a laboratory, here called reproducibility within laboratory, u(Rw) and the second category is the method and laboratory bias, u(bias). The third category is the reproducibility from interlaboratory studies, u(R). The error model used is a simplification of the model presented in the ISO guide 21748. However the first and most important step is always definition of the measurand and specification of the required measurement uncertainty. Starting with this information the handbook then tries to cover all steps in the analytical chain from the arrival of the sample in the laboratory until the data has been reported. It is important to notice that vital parts of the total measurement uncertainty are not included, e.g. sampling, sample transportation. It is recognised that while the recommendations presented do form a valid approach to the evaluation of measurement uncertainty for many purposes, other suitable approaches may also be adopted especially the EURACHEM/CITAC Guide (www.eurachem.com) which, in the second edition, also stresses the use of method validation data. Another good source is the Eurolab guide 2007 (Measurement Uncertainty revisited, www.eurolab.org). The English version of the handbook [1] is available at www.nordicinnovation.net, Nordtest, Tecn. Report TR537.