Tissue-specific protein profile is determined by its function, structure, intensity of metabolism and usefulness. This profile remains under hormonal control. Any disturbance in the general metabolism may be reflected in changes in both protein quantity and quality. These changes can be of low or high specificity, and some can be used as clinical markers of pathological conditions. The aim of this study was to describe and to compare the protein profile of caruncle and foetal villi of bovine placenta that was either properly released or retained. Placental tissues were collected from healthy cows, divided into releasing and retaining foetal membranes, homogenized and subjected to 1D and 2D electrophoresis. Computer-aided analysis of gel images showed essential qualitative and quantitative alterations in protein profile between tissues that were properly released and retained. Alterations concerned both the number of fractions and spots as well as the intensity of staining. This preliminary study provides a general overview of the differences in the protein profile between released and retained foetal membranes. It may allow for selecting the group of proteins or single molecules, which should be further analysed in detail as possible markers differentiating the retention of foetal membranes in cows from placentas that were released spontaneously. The continuation of the study for the identification of particular spots detected in 2D gels is necessary.