A patient with mumps myocarditis is reported. The onset of mumps was typical, with fever and parotid swelling followed by raised virus antibody titres. Atrioventricular block occurred and persisted despite steroid treatment for two weeks. He had an Adams-Stokes attack. A permanent pacemaker was implanted and, thereafter, the patient remained dependent upon it. The published material on conduction disturbance in mumps myocarditis is reviewed.