In two kidney transplant patients, one of whom had panel-reactive antibodies (PRA) before transplantation, a pretransplant negative donor-recipient crossmatch became positive within the 1st week after transplantation. Simultaneously, good graft function deteriorated to a state of anuria. One patient graft biopsy showed a vascular rejection, whilst the other patient biopsy was unrevealing. Both patients were treated with plasmapheresis and a new immunosuppressive drug, 15-deoxyspergualin (DSG). Plasmapheresis was performed for 6 and 9 days, respectively, and DSG was given for 5 days in a dosage of 6 mg/kg body weight per day. One of the patients received methylprednisolone i.v. in addition. During treatment the cross-match became negative and has since remained that way. In both patients the graft function was restored. No adverse effects were seen from the treatment, except for a slight leukocytopenia and thrombocytopenia.