Renal involvement in patients with liver cirrhosis is characterized by renal vasoconstriction, the aetiology of which remains obscure. Endotoxaemia, frequently found in patients with liver cirrhosis and renal failure, has been emphasized as a pathogenic factor. In fifty-seven patients with liver cirrhosis without overt renal failure endotoxin plasma level (Limulus Lysate test), mean renal blood flow (MRBF) (133Xe washout technique), and effective renal plasma flow (ERPF) (p-aminohippurate clearance) were determined. MRBF was decreased in nineteen out of twenty-seven patients, averaging 1.88 +/- 0.51 ml g-1 min-1 (in fourteen controls 3.17 +/- 0.51 ml g-1 ml-1). ERPF was decreased in seventeen out of thirty patients, averaging 380 +/- 164 ml/min (in eighteen controls 624 +/- 127 ml/min). Systemic endotoxaemia was found in sixteen out of fifty-seven patients, levels ranging from 0.62 to 200 ng/ml. No significant difference in renal blood flow values was found between patients with and without endotoxaemia (MRBF = 1.78 +/- 0.51 and 1.93 +/- 0.52 ml g-1 min-1 respectively; ERPF = 429 +/- 119 and 365 +/- 175 ml/min respectively). No significant difference in the frequency of endotoxaemia was found between patients with impaired and unimpaired renal blood flow. Moreover no relation was found between endotoxin plasma levels and MRBF and ERPF respectively. In conclusion in patients with cirrhosis without overt renal failure renal vasoconstriction does not seem to be related to endotoxaemia.