Geotechnical and environmental engineering projects employ thin polymeric geosynthetic barriers in some situation as biodigesters roofing systems and reservoirs or waterproofing systems in areas with low environmental risk. The tensile strength characteristics are considered control properties to be assessed, both during the manufacturing process and in product acceptance phase in the field. Furthermore, it is the analysis of the tensile properties the tool usually chosen to evaluate the behavior of these membranes over time, considering the various agents that could degrade it (weathering, chemical attack, oxidation, ...). Tensile strength properties being of high importance for the identification, characterization and quality control of the products, it is essential to have testing standards whose suitability and repeatability were well evaluated in order to provide values that allow the comparison between products and facilitate the quality and durability controls. A clear definition of procedures becomes necessary when considering that these properties are affected by factors related to the test, such as the influence of the specimen thickness and preparation, tensile speed, distance between grips, type of grips and the system adopted for elongation measurement. Several standards were published for the quality control and specification of polymeric geosynthetic barriers and plastic sheeting and they are widely used by manufacturers and designers. However, there is no consensus on the standard test to determine the tensile behavior, so that test methods producing different results can lead to conflicts and difficulties for the acceptance or rejection of a particular thin product. The proposed paper compares the procedure adopted by American, International and Brazilian standards, and the results obtained in tests with PVC and fPP thin sheets, showing that the standard can significantly change the obtained result.