Preapproval of elective permanent pacemaker insertions in Medicare patients is now mandatory for reimbursement. Of 1,860 requests for approval of an initial pacemaker implant in Massachusetts, 1,494 (80.3%) met strict Medicare guidelines and were approved by a nurse reviewer, and 366 (19.7%) were referred to an independent physician because of a question of appropriateness of indication or type of pacemaker. Only five requests (0.27%) were denied because of an inappropriate indication for pacing. On a second review of these records, an additional eight pacemaker insertions (0.43%) were deemed to have been inappropriately approved. Comparison of the annualized number of pacemaker requests for the study period with those of the 3 years before mandatory approval revealed a reduction of only 3.7%. Thus, contrary to previous findings in other areas of the country, in Massachusetts, inappropriate pacemaker insertions are rare and the effect of the prior approval process is minimal. © 1990.