Risk assessment at national scale is crucial to devise mitigation strategies and policies aimed at disaster risk reduction. Among other building types, school buildings represent a key asset, due to huge consequences of their collapse or unusability in the aftermath of a natural disaster. In this context, this contribution presents the derivation of a seismic fragility model for masonry school buildings, for analysis at regional scale. The derived model includes sets of fragility curves for 120 building macro-classes, defined according to few parameters available in the national school building registry. A limited number of prototype buildings were selected for the analysis. Then, the size of the dataset was increased by varying a series of typological and structural features. The fragility assessment was carried out through a mechanic-heuristic procedure based on the combination of a mechanical approach with a macro-seismic model. Fragility curves were fit as lognormal cumulative density functions, conditional to the peak ground acceleration. The proposed model reflects the characteristics of a stock of existing school buildings representative of the Po Valley, the largest and most populated area of Northern Italy. Lastly, the proposed regionalised model was compared to an analogous fragility sets developed for the entire country. Comparison of results shows the impact of regionalised models in risk assessment, providing more realistic estimates.