Fourteen tree-ring chronologies developed from 788 peatland Scots pines sampled at sites in Estonia, Belarus and Sweden were compared for common growth trends and possible links to regional climate dynamics. Several synchronous growth release events were detected, especially during the 1910s, 1930s, and around 1970 and 1990, indicating that hydrological shifts and associated tree growth responses have been governed by similar forcing mechanisms, at least during the 20th century. In general, the best agreements were observed between the tree populations from Estonia and Belarus, but synchronous growth changes could also be detected between the Swedish and Estonian material. Trends detected in single tree-ring chronologies may be linked to local peatland management or land-use changes, whereas common variations detected at multiple sites are more likely linked to hydrological changes in the peatlands associated with regional climate dynamics. Understanding the links between climate and processes that involve peatland hydrology and vegetation responses is important since peatland ecosystems are key players in the global carbon cycle.