The goal of implants, is to restore the patients stomatognathic system to normal contour, function, esthetics and thereby improvinng speech and health. Despite its high success rates, failures like biological, technical, and esthetic complications do occur in a percentage of cases. Implant failure is a multifactorial process, which can occur right from the selection of the patient, treatment planning, surgical stages, prostheses designing, fabrication and maintenance of implant. A better understanding of the factors associated with implant failure, will provide data for planning future studies, facilitate clinical decision making and ensure implant success. Hence, it becomes mandatory for the clinicians to know ‘why’ the implants fail and how best they can overcome and avoid the problems associated with it. To make the understanding easier the failures are discussed under the following headings: (a) Criteria for success of osseointegrated endosseous implants, (b) Parameters used for evaluating implant failures, © Classification of implant failures, (d) Management of implant failures and (d) Maintenance