Purpose – The public sector worldwide is under pressure to downsize, which has led to mergers of public sector organisations. This paper seeks to bridge the unstudied gap of what happens to organisational reputation after a merger. The paper discusses change and reputation in the public sector, and reports findings of a longitudinal study on stakeholder assessments of four public sector organisations undergoing mergers recently. Design/methodology/approach – Following a theory-driven content analysis, this longitudinal study compares stakeholder assessments of four public sector organisations' reputations a year before an organisational merger with assessments of the two resulting organisations' reputations two years after the merger. Findings – The paper finds that the mergers did not really re-shape reputation, but the once established reputation persevered. Although the organisations faced greater expectations after the merger, only minor changes in reputation were detected post-merger: the reputation for expertise, heavy bureaucracy and trustworthiness remained strong after the merger, but certain traits, such as being international and esteemed, were lost. In both cases, one organisation's prior reputation slightly dominated the new reputation. Research limitations/implications – The findings may be limited to Finland and other Nordic countries, as well as those countries where trust in the public sector is high. Practical implications – Mergers may not change once-established reputations, and hence the improvements desired by mergers may go unnoticed by the different stakeholders. Organisations merging must prepare for increased stakeholder expectations, as the new organisations arise questions. Previous organisational traits may remain in stakeholders' assessments despite any achieved improvements. Originality/value – This paper addresses the gap in studying organisational reputation after public sector mergers, and contributes to both theory and practice by providing insight into the stability of once-established reputations.