The thesis deals with the theme of mosaics and frescoes created in the early Christian period, from the 3rd to the 6th century. At the beginning, the thesis gives a theoretical introduction to the iconography of the early Christian art and painting techniques. Representative mosaic art observed in the context of the architecture in which they were created is discussed. Furthermore, layouts of sacral buildings are presented. The paper deals with the relation of Salona, capitol of the province of Dalmatia, with smaller towns throughout the spread of mosaic patterns that have originated in the Salona’s school-workshop. Given that the production centre was in Salona, most sites with early Christian mosaics were found there. Mosaics are mostly buried and researched according to the pictures available in the literature. Frescoes are found on a small number of early Christian sites because of their fragile technique. Along with the frescoes in basilicas containing ornamental patterns, there are frescoes from Salona with figural motifs. Mosaics and frescoes are compared according to the criteria of originality and quality of the performance. Results of the research give insight into the activities of the Christian community and its expansion.