To determine if an elevated triglyceride concentration can explain the opacity of some cirrhotic ascites specimens, the authors measured triglyceride concentration by Coulter DACOS (Hialeah, FL) on 133 paired serum and ascitic fluid specimens. The specimens were categorized as clear or cloudy by coded visual inspection. In addition, the ascitic fluid specimens were inspected for a lipid supernatant after 48 hours of refrigeration at 4 degrees C. The ascitic fluid triglyceride concentration of the 87 clear specimens was 1.9 +/- 1.0 mmol/L compared with 7.0 +/- 4.6 mmol/L for the opalescent specimens (P less than 0.001). Only 17% of the clear specimens demonstrated any lipid layer after refrigeration, compared with 94% of opalescent specimens (P less than 0.001). The triglyceride concentrations were not significantly different between the serum samples obtained from patients with clear compared with opalescent ascites. The opacity of portal hypertension-related ascites appears to be related to the triglyceride concentration of the fluid.