The success of dental implant therapy depends upon a good amount and quality of bone present around the implant. During the first year of implant placement, most of the crestal bone undergoes resorption and this rate of resorption is 1.5-2mm around the dental implants after the prosthetic restoration which is clinically acceptable. This crestal bone resorption is restricted by many modifications in the implant system. Platform switching is one such concept which can be applied clinically to maintain the crestal bone level and consequently preserving the normal soft tissue contours. Placement of a small diameter abutment on a large diameter implant platform has been proposed as an effective way to control circumferential bone loss around dental implants. The purpose of this review is to discuss the literature dealing with platform switching concept to preserve the crestal bone, the mechanism by which it contributes to maintenance of marginal bone.