We describe a 75-year-old man who developed a vesicular variant of bullous pemphigoid with a distinctive result of immunoblot analysis. Characteristic symptoms consisted of vesiculopapular eruptions with erythematous patches on the arms and legs, many of which fused to form irregularly outlined areas of erythema varying in size. Direct immunofluorescence revealed a linear deposition of IgG at the basement membrane zone of the skin, and indirect immunofluorescence detected circulating IgG autoantibodies at a titre of 1:160, which reacted with the antigens located on the epidermal side of skin split with 1 mol/L NaCl. Immunoblot analysis using epidermal extracts demonstrated the presence of IgG antibodies directed to 150, 205, 240 and 280 kDa proteins as well as to the 180 kDa bullous pemphigoid antigen (BPAG2). All antibodies eluted from nitrocellulose membrane imprints of individual bands with molecular weights of 150, 180 and 205 kDa were found by indirect immunofluorescence to react with the basement membrane zone, whereas those eluted from the bands with molecular weights of 240 and 280 kDa did not. These findings suggest that antibodies directed not only to the 180 kDa BPAG2, but also to 150 and 205 kDa proteins, are involved in the pathogenesis of bulla formation in this patient.