A 16-month-old boy exhibited vesicobullous skin lesions on the lower part of his abdomen, in his genital region, and on the buttocks and extremities. The eruptions presented small, tense bullae with or without erythematous changes of the surrounding skin, some of which clustered around the resolving lesions. Histologic examination of the eruptions showed subepidermal, ultrastructurally suprabasal laminar blister formation with infiltration of the polymorphonuclear cells and large mononuclear cells in the blister cavity. Immunoelectron microscopy revealed IgA deposits at the basilar surface of the basal keratinocytes of the lesional skin, as well as the presence of circulating IgA-class antibodies reacting to the basilar surface of the hemidesmosomes. The eruptions responded well to a combination therapy of small doses of a corticosteroid agent and a sulfonamide. There were neither clinical nor laboratory findings suggesting dermatitis herpetiformis. This case, diagnosed as linear IgA bullous dermatosis of childhood by immunofluorescence microscopy, ultrastructurally had a pathogenic site close to that observed in bullous pemphigoid.