The Asian longhorned beetle (ALB), Anoplophora glabripennis (Coleoptera: Cerambycidae), is one of the most harmful invasive species in Europe and North America, causing enormous economic damage to broadleaved trees growing in urban parks and gardens. As a quarantine species, everywhere it has been introduced ALB has led to the application of expensive eradication programmes often associated with additional indirect costs due to the loss of ornamental value connected with the presence of trees in urban areas. The aims of this article are to quantify the impact of ALB in terms of tree mortality and their ornamental value during the first year eradication of an infestation in Northern Italy, and to perform an economic assessment of the eradication programme vs inaction. During the first year of eradication 367 ALB infested trees were removed fromthe infestation area at a total cost of about € 48 000, comprising scientific advice (21 percent), tree survey (38 percent)andplant removal (41 per cent). The ornamental value of the infested trees was assessed at about € 850 per tree. The ALB eradication programme allowed a reduction of 52 per cent of the damage expected in the following year, corresponding to an ornamental value of about € 300 000. The ornamental value of the saved trees was 6 times higher than the costs for their protection.