In accordance with mentor doc. art. Barbara Horvat Kavazović and Mr. Nikica Milas as artwork's owner, the figurative painting Immaculate Conception by an unknown author was chosen for the subject of the diploma work. In the image of smaller dimensions, in a well-made ornamental frame between two protective sheets of glass, found at one of the antiques fair in Zagreb, the owner recognized its artistic value and handed it into the hands of experts from the Zagreb Academy of Fine Arts in Zagreb, at the Department of Conservation and Restoration of works of art. Given the fact that the existing state of artwork has grown on Mr. Milas's, the need for complete restoration treatments did not exist. Given that it has a large amount of missing areas in the painted layer and the ground layer which would facilitate future penetration of moisture and further loss of layers, and a complete lack of any secondary support, it was decided in agreement with the mentor and the owner, to carry out all the needed conservation and restoration treatments. As a part of this, within the chapter Methods and materials different materials have been researched, their characteristics, compatibility with the original painting technology, and the possibilities of achieving a desired finish. The chapter Conservation and Restoration Research has attempted to locate the painting origin and period since there is not much information about it. The only given information is the paper of smaller dimensions found on the back of the artwork, depicting the alleged historical-artistic events of the time when the painting was made. Comparing the style and shaping of the work of art, as well as the analysis performed on the Department, it helped to give a more accurate picture of the time of emergence the artwork. Finally, the conservation and restoration treatments included the decorative frame without glass as well as the mentioned piece of paper, which was ultimately incorporated into the final presentation of the work.