The goal of this article is to describe the use of in vitro methods as well as in vivo and ex vivo animal models to assess residual allergenicity of hypoallergenic (HA) foods, especially infant formulas. These animal models are also used for testing the oral tolerance-inducing capacities of infant formula; thus, they are very helpful in predicting allergenicity and the tolerogenic potential of HA infant formulas, and in helping to prevent adverse reactions in sensitive infants.