Sponges are important constituents of coral reef ecosystems, including those around the Arabian Peninsula. Despite their importance, our knowledge on demosponge diversity in this area is insufficient to recognize, for example, faunal changes caused by anthropogenic disturbances. We here report the first assessment of demosponge molecular biodiversity from Arabia, with focus on the Saudi Arabian Red Sea, based on mitochondrial and nuclear ribosomal molecular markers gathered in the framework of the Sponge Barcoding Project.We use a rapid molecular screening approach on Arabian demosponge collections and analyse results in comparison against published material in terms of biodiversity. We use a variable region of 28S rDNA, applied for first time in the assessment of demosponge molecular diversity. Our data constitutes a solid foundation for a future more comprehensive understanding of sponge biodiversity of the Red Sea and adjacent waters.