Pemphigus vulgaris is an autoimmune blistering disease caused by antibodies against desmoglein (Dsg) 3. We previously reported that pemphigus vulgaris (PV)-IgG caused the formation of Dsg3-depleted desmosomes in normal human cultured keratinocytes and DJM-1, a human squamous cell carcinoma cell line. In the present study, we injected PV-IgG and normal human IgG into neonatal mice and examined the quantities of Dsg3 in the mouse skin. We showed that injection of PV-IgG into neonatal mice caused suprabasal blister formation and approximately 30% reduction of Dsg3 in mouse epidermal keratinocytes, compared to mice injected with normal human IgG. In addition, we showed that the quantity of Dsg3 in the skin of patients with PV did decrease, as compared to that in healthy volunteers. Our data suggests the reduction of Dsg3 might be relevant to blister formation. These results also suggest that even a partial depletion of Dsg3 may contribute to blistering in PV patients.