The practical part of the master`s thesis on the high altar of the Mary Help of Christians from eponymous church in Sotin made of stucco marble was carried out in a partnership with the Croatian Conservation Institute (CCI). In agreement with Head of Department for Stucco, Consultant conservator-restorer Danuta Misiuda, the leader of the conservation-restoration works on the high altar of the Mary Help of Christians, Senior conservation technician Krešimir Valentak and menthor Associate Professor of Art Alen Novoselec, it was decided that conservation-restoration works for the purposes of this thesis will be carried out on lintel of the altar`s ambulatory. The works were preceded by study, documentation and survey. Data from the literature wich records the place, the object and style were generated through historical and art historical study. As well, a lot of time was dedicated to the study of somewhat forgotten technique and technology of stucco marble on wich the theoretical part of the thesis is focused. Conservation research provided an insight to the condition of the altar. The altar was in pretty bad state, all stratigrafic layers endured severe damages. That is why the biggest amount of attention was directed in finding the most suitable methods for reintegration of all stratigrafic layers. Due to this fact, the plan of conservation-restoration works was suggested. Following the suggested plan, conservation-restoration intervention on lintel of the altar ́s ambulatory was performed. It encompassed cleaning, taking samples for chemical analysis, reconstruction of the wooden substructure, reimburse missing parts of rendering layer and reintegrating the stucco marble layer. Samples were taken for plaster, rendering and pigments analysis. The most demanding part of all conservation-restoration works was reintegration of stucco marble layer. It was executed in traditional technique, by applying multicolored pigmented paste for stucco marble on the rendering layer. It was necessary to make many samples for each pattern of stucco marble layer in order to obtain a pattern as close to the original.