Seven patients suffering from metastatic cancer and all showing objectively measurable tumours were treated with eight sessions of membrane plasma exchange. No other oncological treatment was administered during the period of plasma exchange. The procedure itself was well tolerated and subjective improvement was reported by some patients. No objective tumour regression was observed. Immune complex-like material and inflammatory proteins were efficiently removed. In some patients a decrease in the number of T lymphocytes, due to relative depletion of T mu cells, was noted.