This dataset contains experimental information on Portuguese masonry structures gathered through in situ investigations and laboratory tests carried out by institutions across mainland Portugal and the islands. The collection includes mechanical properties, material characterisation, test setups, dimensional data, geolocation, and reference information. Please cite this publication as: António Simões, Rita Bento, Tiago Miguel Ferreira (2026) Properties of Masonry Structures in Portugal: Proposal of New Correlations with the Masonry Quality Index (MQI), Bulletin of Earthquake Engineering, Springer. https://doi.org/10.1007/s10518-026-02361-8 Dataset Overview, Scope and Purpose This dataset was developed within the scope of CT 115 SC8, the Portuguese Technical Committee for Structural Eurocode Standardisation, dedicated to Eurocode 8: Earthquake Resistance Design of Structures. It has been compiled by a Working Group formed by representatives from universities, national and regional laboratories, and engineering firms across mainland Portugal and the islands. The collection brings together experimental data on Portuguese masonry structures, obtained from in situ investigations and laboratory tests conducted over many years. Its purpose is to support the characterisation of Portuguese masonry typologies and to provide reference mechanical parameters for engineering practice and research. For further information about the project, please visit the project webpage at https://www.masonry.pt/. Dataset Metadata The data are structured as follows: Rows: Each row corresponds to one test entry provided by a contributing organisation. A unique identifier is assigned to every record through the field named AutomaticIdentifier. Columns: Each column corresponds to a variable that describes the specimen, test conditions, and mechanical results. The first row contains the complete list of field names, which follow a consistent naming scheme intended for long-term use and cross-platform compatibility. The fields cover the following groups: Identification and location Masonry and material description Test information, including dimensions, support conditions, and standards Mechanical properties obtained from testing Additional information and source references Variable content: For each entry, the dataset records the location of the test, the type of masonry unit and mortar, details of the cross section, and the nature of the mechanical test performed. Dimensional information includes the width, height, and thickness of the tested panel. Test conditions and any influencing factors are included to support the interpretation of results. Mechanical properties, including compressive strength, tensile strength, shear strength, elastic modulus, shear modulus, cohesion, and unit weight, are provided in consistent units to facilitate comparison. The dataset also includes qualitative descriptors, such as confidence levels and observations, that clarify deviations or construction aspects necessary for a complete understanding of the test results. When available, a reference source is provided for the entry to ensure traceability and enable users to locate the original reports or publications.