Angiotensin II (AT II), but not noradrenaline (NA) provoked greater pressor effects in anaesthetized rats which have been bilaterally nephrectomized for 24-48 h than in control animals which underwent the same surgical procedure 2-3 h previously. Perfused hindquarters and isolated portal veins derived from bilaterally nephrectomized rats did not exhibit supersensitivity to AT II or NA. Aorta strips removed from rats nephrectomized 48 h before showed a selective decrease of sensitivity to AT II. The results of these in vitro assays suggest that the well known increased pressor effect to AT II, observed in nephrectomized rats cannot be accounted for by an increased sensitivity of large arterial and venous vessels or of the femoral vascular bed.