This study investigated the experience of endossoseus implants in the U.K. - how success rates compare with other countries; the common causes of failure; early detection, definition and treatment of the failing implant. Information was gathered by means of a questionnaire sent to 120 centres in the U.K. Thirty-nine centres responded to the survey, reporting on a total of 5328 implants which had been placed over an average time period of 6.5 years. A mean failure rate of 4.3% was reported in the mandible with 16% in the maxilla. The survey showed that 11 different implant systems were in use and that implants were used to support an overdenture in 56% of cases, and bridgework in 26%. The definition of the failing implant and the causes of failure were unclear, with a wide range of opinions given. A combination of methods were used to treat the failing implant including surgical techniques and chemotherapeutic agents, but the long-term success of these treatments was uncertain. Failure rates especially in the maxilla at some of the centres appear higher than have been previously suggested in the U.K. or abroad. Universal agreement on the criteria for 'success' and 'failure' of fixtures is needed along with agreed treatment protocols for the failing implant.