The effect of different cavity finishing methods on in-vitro microleakage of two amalgams (Amalcap non gamma 2 SAS, Tytin) was investigated by the dye penetration method. Amalcap non gamma 2 SAS demonstrated better sealing properties than Tytin. The highest degree of microleakage was observed when the cavities prepared with a diamond coated bur (mean particle size 80 microns) were left unfinished. The degree of marginal leakage in Class-I cavities was reduced by finishing their walls with tungsten carbide or diamond coated finishing burs. Cervical Class-II cavity walls finished with a tungsten carbide or a diamond coated finishing bur demonstrated lower marginal leakage than cervical walls finished with a gingival margin trimmer. Finishing of proximal Class-II cavity walls with tungsten carbide or diamond coated finishing burs followed by removal of the remaining enamel overhangs with a diamond coated file (Cavishape) resulted in a lower degree of dye penetration than finishing proximal walls with a proximal margin trimmer. The results indicate that Class-II cavities with minimal extension of the proximal walls can be effectively finished without using hand instruments.