The structural changes of interfacial transition zone of two concrete systems reinforced by polypropylene/polyethylene and basalt fibers were studied by Raman microspectroscopy. The interfacial transition zone was found in the 0-20 μm in vicinity of quartz/feldspar aggregate surface. The calcium carbonate, ettringite and alite and belite bands were used for determination of interfacional transition zone size by Raman spectroscopy. Similar behaviour has been shown the cement matrix in neighbourhood of PP/PE fibers. There is not observed any concentration gradient of cement hydration product in the vicinity of 1 μm diameter basalt fiber., Vladimír Machovič, František Kolář, Petr P. Procházka, Šárka Pešková and Pavel Kuklík., and Obsahuje bibliografii