Nanocomposites based on (70/30) blends of natural rubber (NR), styrene-butadiene rubber (SBR), and organoclay (OC) have been prepared successfully via melt-mixing process. Effects of the extent of polymers/clay interactions upon the developed microstructure, fatigue life, and dynamic energy loss by the nanocomposites have been investigated. Maleated EPDM (EPDM-g-MAH) and epoxidized NR (ENR50) were employed as compatibilizer. Nanocomposites were characterized by means of X-ray diffractometer (XRD), transmission electron microscope (TEM), scanning electron microscope, atomic force microscopy, root mean square, and dynamic mechanical thermal analysis. EPDM-g-MAH showed more potential in enhancing dispersion of the clay nanolayers and their interaction with rubber phases. More potential for separating and dispersing the clay nanoplatelets with better interface enhancement was exhibited by EPDM-g-MAH as compatibilizer. This was consistent with higher resistance towards large strain cyclic deformations along with more heat build-up characteristics showed by EPDM-g-MAH based nanocomposites especially at compatibilizer/organoclay ratio of 3. Pronounced non-terminal behavior within low frequency region was also observed for melt storage modulus of this nanocomposite, indicating higher extent of intercalation/exfoliation microstructure with reinforced interfaces than the nanocomposite generated by ENR50. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1853-1864, 2012