Five patients with cyclosporin-related haemolytic uraemic syndrome (HUS) following cadaveric renal transplantation were converted from cyclosporin- to tacrolimus-based immunosuppression. All patients had biochemical, haematological and biopsy evidence of HUS at the time of conversion. Four of the patients showed complete resolution of the syndrome within 1 week of conversion with normalisation of haemoglobin, platelets and lactate dehydrogenase levels. In the fifth patient renal function stabilised with slow resolution of the haematological and biochemical parameters. Four of the five patients are still taking tacrolimus, one having converted back to cyclosporin due to marked hair loss. We conclude that conversion to tacrolimus appears to be an effective treatment for cyclosporin-related HUS following renal transplantation.