Fourteen infants presenting with unexplained episodes of weakness or fainting were investigated by repeated Holter monitor recordings and oculocardiac reflexes (OCR). The recordings were then compared with those of 10 normal children in order to try to establish the criteria of vagal hyperreflexia. Results of OCR were collated with those of Holter: there was a good correlation between the length of the cardiac arrest on the OCR and the minimal instantaneous frequency and the maximal change of instantaneous frequency recorded on the Holter. The diagnostic difficulties of these vaso-vagal episodes in infants are emphasized. The potential gravity of these episodes and the possible relation with the sudden infant death syndrome are then discussed in the light of these cases.