We report a case of transient gluten hypersensitivity, demonstrated by jejunal histology at diagnosis, normalization after gluten-free diet, and acute clinical and histological relapse after a challenge with gluten powder at the age of 1 year, resembling that observed in cow's milk protein intolerance. Subsequent provocation tests did not show any alteration. Cases of supposed transient gluten hypersensitivity are rarely reported; our patient is characterized by the acute reaction to gluten challenge associated with a damaged histological picture and depressed levels of complement.