Between 1957 and 1973, a total of 64 children who had complete heart block during intracardiac surgery were treated by one of three methods: (1) No pacemaker: Six of the 13 patients in this group had reversion to sinus rhythm. Seven patients continued to have complete heart block, and five of these died of Stokes-Adams episodes. Two patients continue to have complete heart block without pacemaker insertion. (2) Temporary pacemaker: Seventeen of 25 patients had reversion to sinus rhythm and the temporary pacemaker was removed; the other 8 continued to have complete heart block. Five of the eight died-three of Stokes-Adams episodes and two at the time of cardiac reoperation. Three remain asymptomatic without placement of a permanent pacemaker. (3) Permanent pacemaker: Twenty-six patients had implantation of a permanent pacemaker. Six died of postoperative complications unrelated to heart block or pacemaker implantation. None of the other 20 experienced Stokes-Adams attacks. There was one late death in this group. Although there are problems in using permanent pacemakers and electrode systems, in these patients with operatively induced complete heart block their use was associated with a low mortality rate.