SummaryA comparison of the accuracy of denture bases made from a conventional acrylic and four modified acrylic resins was made with the use of a non‐parametric method. Twenty‐five identical maxillary stone casts were made and five dentures for each resin were processed by conventional compression moulding techniques. The fit of each denture at the molar‐to‐molar region on its cast was evaluated by five evaluators who independently ranked the twenty‐five dentures from best to worst fit after processing, after polishing, and after storage in water at 37°C for 42 days. The ranking data were analysed by Kendall's coefficient of concordance, the Kruskal‐Wallis statistic, and the Mann‐Whitney test. Excellent agreement among observers was obtained. After storage in water, two modified acrylic resins, Hydrocryl and Vitalon II, had a better fit on their casts than the conventional acrylic, Lucitone Hypro. Lucitone 199 had the same and Hircoe had a poorer fit than