Arterial hypertension is frequent after cardiac transplantation. Since cyclosporin was introduced its incidence has risen up to 40 to 100 per cent of the patients. Its date of onset and severity are variable. Arterial hypertension acts on the heart by increasing left ventricular hypertrophy and transplant dysfunction and on the kidney by aggravating the cyclosporin-induced renal impairment which is often present. Several mechanisms have been suggested to account for the occurrence of hypertension in these patients, including poor neurological control of blood pressure, a hypothetical haemodynamic effect and the influence of corticosteroids and cyclosporin. Cyclosporin seems to play the main role. The treatment of this iatrogenic arterial hypertension remains to be precisely determined.