Although several studies have used bogs in order to reconstruct paleoclimatic conditions and the historical trends of pollutants, scientific literature is still rather controversial about the role of ombrotrophic bogs as reliable record of past environmental changes. Consequently, understanding whether all vegetational and climatic ginformationh are effectively preserved in peat deposits during humification becomes an essential aspect to be tested before using bogs as natural archives. The present work focuses on stable isotopic ratios, i.e., 13C/12C (ƒÂ13C), 15N/14N (ƒÂ15N) and 18O/16O (ƒÂ18O), and is based on the assumption that, if bogs are consistent archives of environmental changes, these types of ginformationh should be recorded also into humic acids (HA), i.e. the fraction of peat more recalcitrant and refractory to degradation. Thus, an 81-cm long peat core, covering the last 2000 years, was collected from the Etang de la Gruere bog (Jura Mountains, Switzerland), cut into 3 cm slices, and HA were isolated from each age dated layer. Stable isotopic ratios (ƒÂ13C, ƒÂ15N and ƒÂ18O) were then determined in bulk peat and corresponding HA samples. An increase in the humification degree and a decrease of the C/N ratio were observed along the profile. The ƒÂ13C of both peat and HA showed a significantly similar trend with depth (p=0.0001), and the same significant correlation was observed for the ƒÂ15N (pb0.0001). Also the ratio between ƒÂ13C and ƒÂ15N closely resembled the C/N ratio observed in the peat and in HA (pb0.0001), thus underlining that the trend of these isotopic ratios is preserved along the studied bog profile. Consequently, our data seem to support both the role of HA as recalcitrant, stable molecules with a long-term residence time, and the potential of ombrotrophic bogs to be used as garchivesh of vegetational changes occurring (at least) in the last 2000 years. Although a certain relationship (pb0.05) between peat and corresponding HA was found also for ƒÂ18O, our data did not allow the solving of the issue of its reliability as paleoenvironmental proxy.