Plastics represent a part of our everyday life and their applications can be found everywhere around us. In modern society we need to know their fire technical properties because of their broad use. This thesis focuses on testing plastics polycarbonate(PC) and Poly(methyl methacrylate) (PMMA), that can find their application mostly in civil engineering. Testing was carried out in the notion of international standard STN ISO 1210 (1996) and was performed by two methods, method A where samples were placed in horizontal position and method B where samples were placed in vertical position. Samples were tested for 48 hours in laboratory conditions – reference samples and for 168 hours in 70 °C temperatures, which in the notion of the standard represents aging of the samples. Considering the fire technical properties PC achieved lower flammability with method A, because its samples did not burn up to 25mm limit in difference to PMMA samples, that reached 100mm limit. By the set standard the samples of PC and PMMA classified into according classes: all the tested PC samples (reference samples and samples after aging) with method A fell into class FH-1, reference samples of PMMA fell into class FH-3-34,94 and samples of PMMA after aging fell into class FH-4-41,57. Using the method B reference samples of PC classified into class FV-2, reference samples of PMMA and samples of PC and PMMA after aging fell into 4th class, but in which we can not classify samples by method B according to the standard and that is why they fall into same class as the samples tested by method A with same conditioning. Looking at the results and comparison of total time of spontaneous burning the PC achieved better results, where burning through 100mm limit did not happen. On the basis of the results obtained we can say that PMMA is more combustible material than PC and the position of sample placement has an impact on behaviour of the material.