Physiologic similarities between cirrhotic and septic patients have implicated systemic endotoxemia as a possible mediator of the hemodynamic, neurologic, and hematologic complications observed in patients with cirrhosis of the liver. The recently reported high prevalence of endotoxin in ascites, as well as in portal and systemic plasma, has further incriminated endotoxin of gut origin as the responsible agent. Limulus amebocyte lysate tests were performed upon peripheral plasma of 38 cirrhotic patients; portal plasma and ascites were assayed in 14 and 11 of these patients, respectively. No endotoxin was detectable. We believe that the ubiquity of endotoxin, with the attendant opportunities for specimen contamination, is the most likely explanation for the recently reported high prevalence of endotoxin in the plasma and ascites of cirrhotic patients.