The effects of nanoclay addition into polyamide-6 (PA-6) neat resin and processing parameters on cell density and size in microcellular injection molded components were investigated. The analyses were performed on the sprue section of standard ASTM D 638-02 tensile bars molded based on a fractional four factorial, three-level, L9 Taguchi design of experiments (DOE) with varying melt temperature, injection speed, super critical fluid (SCF) concentration, and shot size. It was found that the presence of nanoclay greatly reduced the cell size and increased the cell density when compared to neat resin processed under identical molding conditions. In addition, cell size distribution at the sprue center was, in general, the largest, gradually decreasing towards the skin for both neat resin and nanocomposite. Finally, in contrast to neat resin, in which shot size and injection speed were important to cell density and all molding parameters affected cell growth, the cell size and density for nanocomposite only depended strongly on shot size.