Elastomers were prepared using organoclays with a reactive organifier. A reactive organifier with a hydroxyl end group to react with diisocyanate was synthesized. For the clay, Laponite RD, a synthetic hectorite clay with a shorter aspect ratio but better dispersibility than montmorillonite was used. The ion-exchanged fraction (IEF) of the organoclays increased with increasing molecular weight of the organifier. The d-spacing was increased from 1.1 nm to 2.08 nm. For the tensile properties, polyurethane nanocomposites with better dispersion of the organoclay showed a larger increase in Young's modulus. The tensile strength showed the highest increase, from 17.1 to 24.8 MPa (45% increase), with only 0.43% of the inorganic additive.