Food allergy represents an increasing health problem, with children being the most affected population. The symptoms can appear within minutes or hours of ingesting the offending food, producing skin manifestations, respiratory, gastrointestinal and anaphylactic reactions in the severe forms. Food allergy is established by the loss of tolerance to food proteins, and is characterized by an altered balance of regulatory T (Treg) cells and the shift to Th2 type cytokines in the intestinal lamina propria. We have described the contribution of different factors in establishing oral tolerance, such as the antigenic exposition route, the gut microenvironment, and the timing of the food introduction. Apart from avoiding the food, immunotherapy is the only intervention which produces oral desensitization to food proteins. Among the underlying immunological mechanisms of oral immunotherapy (OIT) are the changes in humoral immunity (a decrease of allergen-specific IgE and an increase of allergen-specific IgG4) and cellular changes such as the increased number of FoxP3(+) Treg cells. At present, the experiences of OIT with various foods are offering promising results. OIT appears to be safe producing low adverse reactions, and effective in inducing desensitization in most subjects with food allergy.