Nanocomposites based on biodegradable poly(butylene succinate) (PBS) and layered silicates were prepared by melt intercalation. Nonmodified montmorillonite (MMT) and MMTs (DA-M, ODA-M, ALA-M, LEA-M, and HEA-M) organo-modified by protonated ammonium cations {i.e., those of dodecylamine, octadecylamine, 12-aminolauric acid, N-lauryldiethanolamine, and 1-[N,N-bis(2-hydroxyethyl)amino]-2-propanol, respectively} were used as layered silicates. From morphological studies using transmission electron microscopy, DA-M, ODA-M, and LEA-M were found to be dispersed homogeneously in the matrix polymer, whereas some clusters or agglomerated particles were observed for ALA-M, HEA-M, and MMT. The enlargement of the difference in the interlayer spacing between the clay and PBS/clay composite, as measured by X-ray diffraction, had a good correlation with the improvement of the clay dispersion and with the increase in the tensile modulus and the decrease in the tensile strength of the PBS composites with an inorganic concentration of 3 wt %. Dynamic viscoelastic measurements of the PBS/LEA-M nanocomposite revealed that the storage modulus and glass-transition temperature increased with the inorganic concentration (3-10 wt %).