We studied citric acid levels and proinflammatory cytokines (TNF-alpha, IL-6, and IL-8) before and after plasma exchange in 8 patients with acute liver failure. Plasma exchange was performed over a 6 to 7-hour period. At each session, 3.6 to 4.0 1 of plasma was exchanged for the same volume of fresh frozen plasma (FFP). The concentrations of citric acid were significantly increased after plasma exchange above concentrations before exchange (p<0.0001). There were no significant differences in TNF-alpha, IL-6, or IL-8 concentrations (p=0.7222, p=0.9357, p=0.6394, respectively). Thus, plasma exchange with FFP alone may not effectively remove cytokines.