We measured the haemodynamic changes following triglycyllysine vasopressin administration and after addition of nitroglycerin in twelve patients with portal hypertension due to hepatitis B-related cirrhosis. A bolus i.v. injection of triglycyllysine vasopressin at a dose of 2 mg reduced the hepatic venous pressure gradient from 18.5 +/- 3.7 (mean +/- S.D.) to 15.6 +/- 4.0 mmHg, p less than 0.001. However, the cardiac index decreased from 4.8 +/- 1.0 to 3.7 +/- 0.8 l/min m2, p less than 0.001; the heart rate decreased from 79 +/- 15 to 71 +/- 13, p less than 0.01; the right atrial pressure increased from 3.2 +/- 1.9 to 5.3 +/- 2.3 mmHg, p less than 0.001; the mean arterial pressure increased from 92 +/- 13 to 103 +/- 13 mmHg, p less than 0.05; and the systemic vascular resistance rose from 939 +/- 182 to 1367 +/- 310 dyn/s cm-5, p less than 0.001. Furthermore, both mean pulmonary arterial pressure and pulmonary capillary wedge pressure showed a significant increase following triglycyllysine vasopressin administration as compared with baseline values (p less than 0.005). The addition of sublingual nitroglycerin at a dose of 0.6 mg returned all the systemic haemodynamic parameters to baseline levels. On the other hand, nitroglycerin administration caused no further change in the hepatic venous pressure gradient. We concluded that although triglycyllysine vasopressin significantly reduced portal pressure in patients with hepatitis B-related cirrhosis, it produced untoward systemic haemodynamic changes similar to those seen with vasopressin. The addition of nitroglycerin improved the detrimental systemic haemodynamic effects produced by triglycyllysine vasopressin without further reducing the hepatic venous pressure gradient.