The effects on surface roughness of three specific classifications of abrasive motion during the polishing of selected amalgam and resin composite materials were evaluated with a profilometer. Equivalent grit sizes were used to evaluate the character of the surface created by each class of abrasive motion. The motions investigated were rotary (diamond), planar (sandpaper disk), and reciprocal (reciprocating handpiece). Fine, medium, and coarse abrasives were used with each motion. Average roughness values for each abraded specimen were used to compare the effects of the type of motion on the surface. Results indicated that, amonga ll of the combinations of motions and abrasive grits evaluated, the planar motion produced significantly lower surface roughness values on both amalgam and resin composite surfaces.