AbstractSix patients with advanced squamous cell cancers of the head and neck, with serum IgA ≤ 400 mg/dl and IgE ≥ 1000 IU/ml. underwent a trial of six 2‐liter plasma exchanges over a 2–3‐week period. Disease progressed in patients 1. 2. and 4. who died on days 44. 72. and 159. The tumor in patients 3 and 6 regressed significantly. repeatedly in patient 3 over each of four courses of apheresis. Tumor recurred in both patients after cessation of treatment, and they died at days 420 and 79. Patient 5. with inoperable disease, received full‐dose radiotherapy immediately following the course of apheresis. and showed complete response in the primary lesion and a major response in the extensive lymph node metastases, dying on day 421 of apparently unrelated causes. Serum IgE in the three patients experiencing tumor regression rose paradoxically during plasmapheresis. Only patient 3 had an elevated level of soluble E‐receptor suppressor factor prepheresis: the serum of patient 6 was lymphocytotoxic prepheresis but this activity decreased or disappeared during each of the exchanges studied. Controlled trials are