The authors have based their study on recent research of cardiac anaphylaxis in vitro and studied the cardiac involvement in vivo, by Holter trace in a group of 12 children with food allergy in basal period (food allergens exclusion) and during food allergens reintroduction. In the same time the involvement of respiratory apparatus was followed by RAW's insp.esp. study. The results showed contemporaneously at the RAW's rise a mean increase of cardiac frequency of slight moment when the frequency was computed during 24 h, but evident in challenge phase. The cardiac frequency study in "late" phase of reply at the food allergens challenge showed a heavy and significant increase of cardiac frequency and extrasystole.