<p>The continuous discharge of synthetic dyes into aquatic systems poses serious environmental and public health concerns. Although numerous studies have investigated natural and modified clays for dye removal, the influence of regional mineralogical diversity, clay purity, and experimental methodology on adsorption performance remains insufficiently addressed. This review provides the first critical synthesis dedicated specifically to Tunisian clay deposits, examining the adsorption behavior of raw and surface-modified clays in relation to their geological origin and mineralogical composition. Clays rich in smectite, kaolinite, halloysite, and palygorskite are evaluated based on reported batch adsorption studies, with particular attention to cation exchange capacity, surface area, structural features, and impurity content. The effects of common modification strategies including acid activation, iron impregnation, and magnetite coating are critically assessed in terms of their impact on surface chemistry and practical applicability.</p><p>The analysis indicates that raw Tunisian clays exhibit a strong affinity for cationic dyes, with removal efficiencies typically ranging from 84% to 97%, whereas the adsorption of anionic dyes remains inherently limited under neutral conditions. Surface modifications generally result in consistent but moderate performance enhancements by increasing surface reactivity, introducing new active sites, or enabling magnetic recovery. However, large variations in reported adsorption capacities are shown to be strongly influenced by experimental design rather than intrinsic clay properties. Overall, Tunisian clays are best regarded not as direct competitors to high-capacity engineered adsorbents, but as low-cost, locally available, and environmentally sustainable materials suitable for decentralized wastewater treatment, particularly in pre-treatment and polishing applications for cationic dye removal.</p>