SummaryApproximately 25% of infants tested released>9% of their blood basophil histamine content in the presence of cow's milk proteins, indicating a degree or level of latent anaphylactic sensitivity to these allergens. Approximately 10% of infants show a considerably higher level of sensitivity (14‐63% histamine release). These findings fulfil an essential tenet of the modified anaphylactic hypothesis for cot‐de