Eleven sera from patients with Brazilian pemphigus foliaceus were tested for their ability to transfer the characteristic epidermal lesions of pemphigus to monkeys. Sera were injected one, two or three times intradermally. Intraepidermal acantholytic microbullae were frequently observed following two or three injections of sera with high pemphigus antibody titers, but only irregularly following single injections of such sera.