Polyamide 6 hydrophobic clay composites were prepared from two organophilized montmorillonites and from a nontreated layered silicate. An ω-amino acid and an aliphatic amine were used for treatment to assure coupling and weak interaction of the components, respectively. Homogenization was carried out by melt-mixing, followed by injection molding to prepare specimens for composite testing. Matrix and silicate structures were characterized by X-ray diffraction, while the melting and crystallization characteristics of polyamide were determined by differential scanning calorimetry. Tensile properties, impact strength and heat deflection temperatures were determined as a function of the layered silicate content. The results obtained confirmed published results that layered silicates promote the formation of the γ modification of polyamide. Partial exfoliation was achieved with both fillers, the extent of which differed slightly in the two cases. The mechanical properties of the composites depend very much on the type of organic compound used for the treatment of the layered silicate. An analysis of the results proved that although many factors change both with the type of treatment and filler content, the dominating factor determining composite properties is interfacial interaction. Changing interfacial adhesion determines micromechanical deformation processes and the overall performance of the composites.