The morphology and dynamic mechanical properties of poly (acry lonitrile-butadienestyrene) (ABS)/polycarbonate (PC)/clay nanocomposites were investigated. From the studies of the transmission electron microscopy (TEM) analysis of the ABS/PC (70/30 wt%) nanocomposites with clay, it was observed that most of the clay existed in the ABS phase and the interface of the ABS and PC. From the studies of the scanning electron microscopy (SEM), droplet size of the PC in the. ABS/PC/clay nanocomposites did not change significantly with the clay and has been found to be from 1.0 to 1.5 pm when the clay was added up to 5 phr. The small difference of the droplet size of the PC was maybe due to the similar values of the viscosities of the dispersed phase (PC) and continuous phase (ABS). From the dynamic mechanical properties of the ABS/PC/clay nanocomposites, the storage modulus was increased by the addition of the clay at the rubbery state between 120 and 150 degrees C. From the studies of the tan 6 of the ABS/PC/clay nanocomposites, it was shown that double tan 6 peaks were observed. The height of the lower temperature tan 6 peak was decreased from 4.5 to 3.3 when the clay was increased up to 5 phr. The decrease of the height of the lower tan 6 peak in the ABS/PC/clay nanocomposites suggested that the ABS chain motion was restricted by the clay in the ABS phase.