A randomised study was performed to assess the influence of prophylactic permanent pacing on the incidence of late sudden death in patients surviving transient complete atrioventricular block with acute anterior myocardial infarction. Fourteen patients were studied, of whom ten died within two years, confirming the high overall late mortality in this group. The deaths included eight of the nine paced patients, of whom seven died suddenly. We conclude that prophylactic permanent pacing is not warranted in patients surviving transient complete atrioventricular block with acute anterior myocardial infarction.