Alemtuzumab (MabCampath; ILEX Pharmaceuticals, Geneva, Switzerland) is a humanised monoclonal antibody directed against CD52. It belongs to a new group of monoclonal antibodies with anti-neoplastic effects used in chronic lymphocytic leukaemia (CLL) either as first-line treatment or in those cases resistant to alkylating drugs. Paraneoplastic pemphigus (PNP) is a severe mucocutaneus disease mostly associated with B-cell lymphoproliferative disorders. Independent of the course of the underlying malignancy, this disease is often resistant to conventional immunosuppressive treatment and may lead to death as a result of infectious complications.