From 1983 to 1997, we have studied ten children with complete atrioventricular block likely due to myocarditis in order to assess its prognosis and to define a therapeutic strategy. Their age ranged from 6 days to 16 years (median: 4.1 years). All were admitted for sudden complete block, with symptoms in seven: syncope or fainting, seizures, collapse. Three had an asymptomatic bradycardia which was detected on routine auscultation in children with fever or already hospitalized; fever was present in 5. The disease was related to infection on biological data in 4 cases (1 listeriosis and 3 seroconversions for Epstein Barr or cytomegalic or Coxsackie B viruses), on a myocardial biposy in 1 case and on scintigraphic data in 1 case. In the remaining 4, indirect arguments were considered such as infectious context, normal recent ECG, favourable outcome. Five children were given intravenous isoprenalin with ventricular tachycardia in 3. Five were treated with steroids and 3 with specific antiviral agents. Seven patients were paced temporarily. One child died, 6 recovered totally and 3 have a permanent block with a definitive pacemaker implanted in 2. In conclusion, sudden acquired complete atrioventricular blocks are often ill-tolerated in children and have to be treated with transient pacing. Recovery occurs as a rule but some of these blocks may be definitive. Infective myocarditis is likely to be the cause of the disease even if the pathogen agent cannot always be identified.