It has been sufficiently established that the so-called small vessel vasculitis results from hypersensitivity reactions to various endogenous or exogenous antigens, and that, in most cases, the pathogenic mechanism is the deposition of immune complexes in the blood vessel wall. Among the therapeutic protocols that have been applied recently, plasma exchange (PE) received little attention, and only a few cases have been treated accordingly until now. Here, we present a patient with diffuse cutaneous necrotizing vasculitis, in whom PE proved to be of irreplaceable benefit in halting the progression of the disease. When PE was discontinued, the disease relapsed in spite of therapy with steroids and heparin. A second series of PE again controlled the disease activity. The authors point out that PE was of unique value pending the effects of treatment with cyclophosphamide, which remains the essential therapeutic agent.