Today's global markets, where products from around the world are appearing, require continuous verification of compliance with the locally required quality levels set by the particular demands to which these products are placed. Applying quality control standards unifies quality testing and defines the requirements that a product must meet. The examination body, the laboratory in which the fulfilment of the set requirements is carried out, have to be professionally and technically qualified to work, which is confirmed by the accreditation procedure performed. General requirements for the qualification of testing and calibration laboratories are given in the standard HRN EN ISO / IEC 17025, and their accreditation is carried out according to this standard. In November 2017, a new edition of ISO / IEC 17025: 2017 was released, which brings some changes over the previous 2005 edition. The changes have been adapted to the new circumstances in which the activities of today's modern laboratories are taking place, primarily concerning the technical part, vocabulary, development of IT technology and compliance with the latest edition of the ISO 9001 standard. The diploma paper gives a detailed overview of the new edition of the standard HRN EN ISO / IEC 17025 and analyzes the changes made by this standard compared to the 2005 edition. The example of preparation for accreditation in accordance with the standard HRN EN ISO / IEC 17025: 2017 is described in detail on the case of the Laboratory for Roads of the Faculty of Civil Engineering, University of Zagreb, which deals with testing of geosynthetic materials. The paper gives a brief overview of the Laboratory, its development and current activities as well as the basic equipment it possesses. The Laboratory is in the process of accreditation for the field of geosynthetics. Within the framework of the diploma work, a brief overview of types and application fields of these materials as well as the testing method is given. The diploma thesis describes the method of testing the tensile properties of geosynthetics on wide strips, as one of the testing procedures undergoing the accreditation process. Testing of tensile properties of geosynthetic materials on wide strips shall be carried out by the European standard HRN EN ISO 10319: 2015 Geotextiles - Wide-width tensile test, Tensile testing of geosynthetic materials on wide strips. The method applies to most geotextiles, including woven geotextiles, non-woven geotextiles, geocomposites, geogrids and felt.