This thesis is dedicated to the study of the influence of gamma radiation on canvas’ microbiota. In particular, a fungus of the genus Cladosporium was used in the experiment, which was recognized as one of the most resistant species of fungi, as well as microbes in general, to gamma radiation. The background motive for conducting these types of research is actually the preservation and prevention of damage of cultural heritage objects which value is invaluable. Namely, gamma radiation has proven to be an extremely useful method of sterilizing objects, whose advantages, but also potential disadvantages, are listed in this paper. The thesis was done in cooperation with the Ruđer Bošković Institute (RBI) in Zagreb, where samples were previously prepared and irradiated. Linen cloth, cut into equal pieces, homogenized and previously sterilized in an autoclave, was used in the experiment. The effect of gamma radiation on two groups of samples (one group inoculated with a species of the genus Cladosporium, while the other was not) at different combinations of dose and dose rate of radiation was investigated, and the number of surviving colonies under certain conditions were observed after inoculation and incubation. The radiation doses used were 2, 5, 10, 15 and 20 kGy, velocities of 0.04, 0.1, 0.2, 0.4 and 6.7 Gy / s. The results showed an unexpected absence of Cladosporia, whose colonies replaced colonies of unidentified white yeast that survived even at higher radiation doses. The radiation dose of 20 kGy was the most effective, although even with that radiation some colonies survived, and in terms of speed, the efficiency is shown by the lowest doses of 0.04 and 0.1 Gy / s, as well as the highest speed of 6.7 Gy / s. It is necessary to make an accurate identification of the unknown yeast in order to be able to discover the cause of its appearance.