Cyclosporine A (CsA) seems to exert direct effects on blood pressure and diurnal blood pressure alterations. After kidney transplant about 60% of the recipients are suffering from such alterations. In the present study, blood pressure profiles of 15 FK506-treated kidney transplant patients were compared to recipients with CsA immunosuppression. Both groups showed no statistical differences in number, kidney function, age, body weight, sex distribution and time after transplantation. Mean arterial blood pressure in FK506-treated patients at daytime was 105 +/- 2.5 mmHg, at night 109 +/- 3.0 mmHg. Systolic blood pressure difference was 2.3 mmHg, diastolic day/night blood pressure difference 0.6 mmHg, and the difference of the heart frequency 6.8 beats/min. Cyclosporin A-treated patients showed a mean arterial blood pressure during the day of 107 + 2.6 mmHg, at night-time a mean arterial blood pressure of 107 + 3.4 mmHg was measured. The diurnal blood pressure alterations of systolic blood pressure were 0.9 mmHg, diastolic blood pressure difference 3.5 mmHg respectively, the heart frequency showed a difference of 4.4 beats/min. Both, FK506-treated patients and patients with CsA immunosuppression exhibit reduced diurnal blood pressure alterations. Furthermore, mean arterial pressure in both, FK506 and CsA-treated patients was elevated and showed no statistical differences between the groups. In FK506-treated patients, however, antihypertensive therapy was less intensive. Concerning arterial blood pressure and diurnal blood pressure alterations, FK506 offers no advantages as compared to cyclosporine A. The reduced usage of antihypertensive drugs, however, may give evidence for lower hypertensive properties of FK506 as compared to CsA.