Cyclosporine and tacrolimus are potent inhibitors of the calcineurin-dependent cytokine synthesis in activated lymphocytes. In renal transplant patients tacrolimus is more powerful in preventing severe and refractory rejections, even when compared with the new cyclosporine microemulsion formulation. Both drugs are equally nephrotoxic, but tacrolimus induces less hypertension and less pronounced hyperlipidaemia, Especially in some categories of patients, a higher incidence of de-novo diabetes mellitus is seen with tacrolimus therapy. Curr Opin Nephrol Hypertens 8:669-674. (C) 1999 Lippincott Wiliiams & Wilkins.