The surface morphology of plasma polymerized methyl methacrylate films was investigated using atomic force microscopy. It was found that the plasma polymer surfaces consist of nanometer scale growth columns. The average grain size of the growth columns increases with deposition time. For the same deposition time, the average grain size is proportional to pressure and deposition power. It was deduced that microscopic properties of plasma polymers are not uniform through the bulk of the plasma polymer films even though the external deposition parameters are held constant.