A novel segmented polyurethane(Pu)/clay nanocomposite has been synthesized by polyurethane and organoclay. 12 aminolauric acid (12COOH) and benzidine (BZD) were used as swelling agents to treat Na+-montmorillonite and for forming organoclay (12COOH-mont acid BZD-mont) through ion exchange. The nanometer-scale silicate layers of organoclay were completely exfoliated in PU in the cases of 1, 3 and 5% 12COOH-mont/PU and in the cases of 1 and 3% BZD-mont/PU nanocomposites as confirmed by X-ray diffraction pattern and transmission electron microscopy studies. The segmented structures of PU were not interfered by the presence of the silicate layers in these nanocomposites as evidenced by their glass transition and degree of phase separation from differential scanning calorimetry and Fourier transform infrared measurements. A two-fold increase in the tensile strength and a three-fold increase in the elongation were found for 1% BZD-mont/PU as compared to that of pure PU. Additionally, both 1% 12COOH-mont/PU and 1% BZD-mont/PU exhibited lower water absorption properties than that of pure PU.