Layered double hydroxides intercalated by long-chain anionic species were prepared and characterized by X-ray powder diffraction.The linear carboxylates are greatly disordered along the stacking direction but dimer fatty acids with planar aromatic moieties show regular X-ray patterns. Alkylarylsulfonates and petroleum sulfonates aggregated in the interlayer spaces forming bimolecular films of constant thickness, which produce integral series of basal, reflections in the X-ray diagrams. Solubility and gel strength of prepared exchanged layered double hydroxides were tested in an oil base drilling fluid formulation and applications of these compounds were compared with conventional organophilic clays.